We've compiled a glossary of baseball terms from around the web to help get you up to speed.

Each definition included in our essential list of baseball terms features the original source page to allow you to explore even further.


A

Ace

"Ace" typically refers to a team's No. 1 pitcher, though it can also be used to describe an elite pitcher in general. Therefore, a team with multiple elite pitchers is said to have more than one ace.

Source: MLB

Active Spin

Statcast refers to the spin that contributes to movement as Active Spin.

Not all spin actually contributes to a pitch's movement. For a football, or a bullet, none of the spin contributes to movement, and so, a football or a bullet has 100% Inactive Spin. In order for a baseball to have Inactive Spin, you would twist your arm slightly so that the baseball is thrown more like a football. The more the baseball is thrown like a football, the more the spin of a baseball will go from Active Spin to Inactive Spin.

When thrown with pure topspin or backspin, then 100% of the spin contributes to movement. You can also throw a pitch with some side-action so that some of the deflection will go up or down, and some will go side to side. All of this is Active Spin.

In 2019, Rich Hill had 100% Active Spin for his curveball -- he was getting the most out of his spin. For four-seam fastballs, Justin Verlander led with 98.5% Active Spin, meaning he was almost entirely optimizing his spin

Source: MLB

Adjusted Earned Run Average (ERA+)

ERA+ takes a player's ERA and normalizes it across the entire league. It accounts for external factors like ballparks and opponents. It then adjusts, so a score of 100 is league average, and 150 is 50 percent better than the league average.

For example, Mariano Rivera's 2.21 career ERA was 105 percent better than the MLB average during the time he pitched (including adjustments for park and league). That gives him a 205 career ERA+ (the best all-time).

The formula

League ERA, adjusted for park factors x 100 / ERA.

Why it's useful

ERA is the most universally accepted tool for measuring the performance of a pitcher. But ERA+ attempts to level the playing field for all pitchers by adjusting for the impact their home ballpark had on their performance.

Source: MLB

All-Star Ballot

All-Star Game starters (except for starting pitchers and the National League's starting designated hitter) are chosen via fan vote, which is broken up into two periods (as of 2019).

After a 25-day Primary Round, the top three vote-getters at each position (top nine in the outfield) per league advance to the Starters Election. At that point, vote totals are reset, and fans have a 28-hour period to vote on starters from the list of finalists at each position.

Finalists who don't win the Starters Election at their position are not automatically added to All-Star rosters, so after the starters are selected by fans, the NL has 24 roster spots to fill, while the AL has 23.

Pitchers and position-player reserves

All of the pitchers and position-player reserves are chosen through a combination of player ballot selections and choices made by the Commissioner's Office.

There are 32 roster spots for each league, with 20 position players and 12 pitchers per side. The player ballots account for 16 players in the NL and 17 in the AL -- eight pitchers (five starters and three relievers), as well as one backup for each position (including DH in the AL). The Commissioner's Office is responsible for selecting eight NL players (four pitchers and four position players) and six AL players (four pitchers and two position players). At this stage, MLB must ensure that every club is represented by at least one All-Star selection.

If an elected starter is unable to play, the reserve who received the most votes on the player ballot at that particular position moves into the starting lineup. The roster replacement is chosen by the Commissioner's Office.

If a player-elected reserve position player must be replaced, the next in line on the player ballot becomes a reserve. Once the top three finishers on the player ballot at a given position are covered, then it becomes a selection by the Commissioner's Office.

The two teams are managed by the previous year's World Series skippers, and they make the decisions on batting orders and starting pitchers. The NL manager also chooses the starting DH for his league. Prior to 2011, the DH rule was used only if the game was being held in an AL park.

History

The All-Star Game fan voting process was overhauled in 2019. Previously, the top vote-getter at each position during a single voting period advanced straight to the All-Star starting lineup.

From 2002-18, the final roster spot in each league was determined by what was known as the Final Vote, with fans having a chance to choose from five players in each league.

A change made in 2017 resulted in All-Star skippers no longer having a say in selections, so there's no longer the potential for any perceived conflicts of interest.

Fans were able to select the starters for each league in each of the first two MLB All-Star Games (1933, 1934), and from 1947-1957. The two All-Star Game managers picked the teams from 1935-1946.

In 1957, Reds fans were accused of stuffing the ballot box, with seven Cincinnati players being voted to start the All-Star Game. In response, Commissioner Ford C. Frick replaced Gus Bell and Wally Post with Willie Mays and Hank Aaron. Frick also eliminated fan balloting, with players, managers and coaches selecting the All-Star rosters from 1958-1969. Fan balloting was restored in 1970.

Source: MLB

Ambidextrous Pitchers

A pitcher must visually indicate with which hand he will use to pitch prior to the start of a plate appearance. This can be accomplished simply by wearing his glove on his non-throwing hand and placing his foot on the pitching rubber. Barring injury, he is not permitted to pitch with the other hand until the batter is retired, becomes a baserunner or is removed for a pinch-hitter.

The pitcher is allowed to pitch with the opposite hand mid-plate appearance should he incur an injury with the other, but he is then barred from pitching with the injured hand for the rest of the game.

Source: MLB

Appeal Plays

The defensive team can appeal certain plays to alert the umpires of infractions that would otherwise be allowed without the appeal. Appeal plays are not the same as a manager asking the umpire for an instant-replay review.

An appeal can be made when the offensive team bats out of turn. Baserunning instances that are subject to appeal include a runner failing to tag up correctly on a caught fly ball, a runner failing to touch the bases in order -- either when advancing or retreating -- a runner failing to return to first base promptly after overrunning or oversliding it, and a runner failing to touch home plate and making no attempt to return to it.

No runner may return to touch a missed base after a following runner has scored. And when the ball is dead, no runner may return to touch a missed base after he has touched a base beyond the missed base. That means a batter who hits a ground-rule double or a homer can be called out on appeal if he misses first base and doesn't correct his error before touching second.

Appeals must be made before the next pitch or attempted play, or before the entire defensive team has left fair territory if the play in question resulted in the end of a half-inning. The appealing team must make clear their intention to appeal, either via verbal request or another act that unmistakably indicates its attempt to appeal.

Source: MLB

Appearance (App)

A pitcher is credited with an appearance if he pitches in a given game. When a pitcher enters the game -- barring an injury while warming up -- he must face at least one batter. When crediting pitchers with an appearance, it does not matter whether the pitcher started the game or pitched in relief.

Appearances can be tricky, because managers inevitably want to limit the total number of appearances by their pitchers to keep them fresh. But not every appearance is created equal. With this in mind, managers must determine when their pitchers are taxed and in need of a day off.

In A Call

"game," "game pitched"

Source: MLB

Arm Strength (ARM)

Arm Strength is defined as the maximum velocity of any throw made by a fielder -- with the max velocity always being at the release point, due to physics. It can be used to evaluate outfielders on attempted assists, catchers on stolen base and pickoff throws, and infielders on throws across the diamond. Fielders -- especially outfielders -- often get a running start before throwing. As a result, the velocity on their throws can exceed that of pitchers, who throw to batters from the mound.

Putting a quantifiable number on the strength of a fielder's arm helps to evaluate the effectiveness of that arm. However, Arm Strength is not the only component of a good throw. Along with velocity, the accuracy of the throw is very important, as is the trajectory. A 90 mph throw from the outfield that bounces three times will inevitably lose speed each time it hits the ground.

In A Call

"throw velocity," "He made a X mph throw"

Source: MLB

Around-the-horn

"Around-the-horn" describes a ground-ball double or triple play that starts with the third baseman and involves a throw to second followed by a throw to first.

"Around-the-horn" can also be used to describe when the infielders throw the ball to one another following an out with no men on base. After a strikeout with nobody on base, the catcher typically starts the "around-the-horn" exercise by throwing the ball to the third baseman.

Source: MLB

Assist (A)

An assist is awarded to a fielder who touches the ball before a putout is recorded by another fielder. Typically, assists are awarded to fielders when they throw the ball to another player -- but a fielder receives an assist as long as he touches the ball, even if the contact was unintentional. For example, on a line drive that strikes the pitcher before caroming to the shortstop, both the pitcher and shortstop are awarded an assist if the out is made on a throw to first base.

There is an assist awarded on most ground-ball outs -- because most ground-ball outs require a defender to throw the ball to another defender. However, there can also be assists on fly balls -- when a runner tries to advance, but the outfielder (or in rare cases, the infielder) throws him out or doubles him off.

There is a maximum of one assist per player per out recorded. If a player touches the ball twice in a rundown, where the runner is eventually tagged out, that player is only credited with one assist for that out. Pitchers are not awarded assists for strikeouts.

In A Call

"gets the assist"

Source: MLB

At-bat (AB)

An official at-bat comes when a batter reaches base via a fielder's choice, hit or an error (not including catcher's interference) or when a batter is put out on a non-sacrifice. (Whereas a plate appearance refers to each completed turn batting, regardless of the result.)

At-bats are used as the denominator when determining batting average and slugging percentage. Players who bat higher in the order will typically finish the season with more at-bats than players who hit toward the bottom. Similarly, players who walk infrequently also typically record a higher-than-usual number of at-bats in a season, because walks do not count as at-bats.

In A Call

"times at bat," "turns at bat"

Source: MLB

Automatic Runner

As part of MLB's health and safety protocols during the COVID-19 pandemic, all half-innings after the ninth will begin with a runner on second base in the 2020 regular season. This rule will not be in place for the 2020 postseason or the 2021 campaign.

The runner placed on second base at the start of each half-inning in extras will be the player in the batting order immediately preceding that half-inning’s leadoff hitter, or a pinch-runner. So, if the No. 7 hitter in the order is due to lead off, the No. 6 hitter (or a pinch-runner for the No. 6 hitter) would be placed on second base.

If the automatic runner comes around to score, an earned run will not be charged to the pitcher.

Source: MLB

B

Balk (BK)

A balk occurs when a pitcher makes an illegal motion on the mound that the umpire deems to be deceitful to the runner(s). As a result, any men on base are awarded the next base, and the pitch (if it was thrown in the first place) is waved off for a dead ball.

Exactly what constitutes a balk is summed up in section 8 of the MLB rules, which describes a legal pitching delivery.

Pitchers with high balk totals are also generally adept at picking runners off, this being because their moves to first base are typically so deceptive that they border on being illegal. Any umpire, if he notices an illegal movement by the pitcher, can call a balk.

Origin

The specific rules for balks were first introduced in 1898 to prevent pitchers from intentionally deceiving baserunners. Without balk rules, pitchers had any means of fooling baserunners, who had to act conservatively on the bases as a result.

In A Call

"free advancement"

Source: MLB

Ballpark Factor

Ballpark factor, at its most basic, takes the runs scored by Team X (and its competitors) in Team X's home ballpark and divides the figure by the runs scored by Team X and its competitors in Team X's road contests. Often times, that number will be ever-so-slightly adjusted if a team doesn't play the same opponents at home as on the road.

For example: In 2018, 849 runs were scored at Coors Field, and 676 runs were scored in Rockies games away from Coors Field. Coors Field had a park factor of 1.271, when looking at runs scored.

The same exercise can be done with other stats, such as home runs, triples, doubles, etc.

Why it's useful

Park factor is a great way of determining the extent to which a stadium favors hitters or pitchers. It isn't affected by the teams or players involved, because those teams and players are also playing games in other stadiums. It simply compares how easy it is to score, from one ballpark to another.

Source: MLB

Baltimore Chop

A "Baltimore chop" is a chopper that takes a high bounce near home plate, allowing the runner to reach first safely.

Origin

The Baltimore chop came from the Orioles of the late 19th century. With runs hard to come by in the dead ball era, the Orioles hatched a plan: They instructed their groundskeeper to pack the dirt in front of home plate (legend has it he once even put down a concrete slab) so that speedsters like John McGraw and Willie Keeler could leg out infield singles.

Source: MLB

Barrel

The Barrel classification is assigned to batted-ball events whose comparable hit types (in terms of exit velocity and launch angle) have led to a minimum .500 batting average and 1.500 slugging percentage since Statcast was implemented Major League wide in 2015.

But similar to how Quality Starts have generally yielded a mean ERA much lower than the baseline of 4.50, the average Barrel has produced a batting mark and a slugging percentage significantly higher than .500 and 1.500, respectively. During the 2016 regular season, balls assigned the Barreled classification had a batting average of .822 and a 2.386 slugging percentage.

To be Barreled, a batted ball requires an exit velocity of at least 98 mph. At that speed, balls struck with a launch angle between 26-30 degrees always garner Barreled classification. For every mph over 98, the range of launch angles expands.

For example: A ball traveling 99 mph always earns 'Barreled' status when struck between 25-31 degrees. Add one more mph -- to reach 100 -- and the range grows another three degrees, to 24-33.

Every additional mph over 100 increases the range another two to three degrees until an exit velocity of 116 mph is reached. At that threshold, the Barreled designation is assigned to any ball with a launch angle between eight and 50 degrees.

Note: The red-shaded area in the graphic above illustrates the exit velocity and launch angle combinations that yield Barreled status in 100 percent of cases.

Additional resources
• Statcast introduces Barrel metric

Source: MLB

Baseball Age (Seasonal Age)

A player's baseball age indicates how old he is as of July 1 in a given season.

The purpose of baseball age is to establish one age per season for each player, even if a player has a birthday during the season and spends parts of the campaign at two different ages. A given season will often be referred to as a player's "age-x season," with "x" being the player's baseball age.

Note: Baseball age is not an official metric, but it is widely used in baseball literature and media.

Examples

Mike Trout was tied for seventh all time in homers through a player's age-25 season with 201 through the conclusion of 2017. Although he was 26 years old by the end of the 2017 campaign, it is considered his age-25 season because he didn't turn 26 until Aug. 7, and, thus, was 25 on July 1, 2017. As a result, Trout can be said to have tallied 201 homers through his age-25 season.

Source: MLB

Baserunner

Baserunners stand on or close to first base, second base and third base at the time a pitch is thrown. Once the pitch is thrown, baserunners can try to advance to the next base -- on a stolen-base attempt or after the ball is put into play. The ultimate goal of a baserunner is to score.

A baserunner can reach base safely after drawing a walk or recording a hit. Once on the bases, he attempts to advance base-to-base before reaching home plate without being tagged or forced out. In no circumstances can a baserunner skip a base.

A runner can also reach base after recording an out during his time at the plate. Such happens most frequently when a batter hits into a "fielder's choice," which occur when a fielder -- usually an infielder -- opts to field a batted ball and retire a runner at second, third or home opposed to throwing to or tagging first base to retire the batter-runner.

Since fielders have a right to occupy any space needed to catch or field a batted or thrown ball, runners are not given the "right of way" on the bases. If a runner is adjudged to have interfered with a defensive team's efforts, then the runner, the batter -- or both the runner and batter -- can be declared out for interference.

In such cases, the ball will be declared dead and all runners must return to their last legally occupied base at the time of the interference.

On the other hand, baserunners have the right to advance on the bases without being obstructed by the fielding team (except in cases when the fielder closest to the runner is in the process of making a defensive play). If a baserunner is obstructed, he is entitled to whatever base the umpire adjudges he would have reached if not for the obstruction.

Source: MLB

Baserunners Per Nine Innings Pitched (MB/9)

Baserunners per nine innings pitched tells us the average number of baserunners allowed by a pitcher for every nine innings pitched. For the purpose of this statistic, "baserunners" include men who reach on hits, walks and hit-by-pitches. Errors and fielder's choices do not count.

Source: MLB

Batted Ball Event (BBE)

A Batted Ball Event represents any batted ball that produces a result. This includes outs, hits and errors. Any fair ball is a Batted Ball Event. So, too, are foul balls that result in an out or an error.

Batted Ball Events are a fundamental part of Statcast data. They are used as the denominator when determining batting metrics such as average Exit Velocity and average Launch Angle. All Batted Ball Events by a given hitter are used to determine these averages.

In A Call

"events," "balls in play"

Source: MLB

Batter

Batters stand a few inches to the right or left of home plate and attempt to put the ball in play against an opposing pitcher. Right-handed batters stand on the third-base side of home plate, and left-handed batters situate toward the first-base side of the plate.

Each team's lineup has nine batters, with each hitter receiving three to five plate appearances in a typical nine-inning game. Batters deliver optimum production when they record home runs -- which always result in the creation of one to four runs scored -- but they always offer value via base hits, extra-base hits, walks and sacrifices.

Batters wear helmets to protect their heads from pitches that badly miss the strike zone. They also wear batting gloves to protect their hands and, on occasion, don elbow pads and shin guards.

Source: MLB

Batter's Box

A regulation baseball field has two batter's boxes -- one on the left side and one on the right side of home plate -- drawn using the same chalk as the baselines. From the pitcher's point of view, left-handed batters stand in the batter's box on the left side of the plate and right-handed batters stand in the batter's box on the right side of the plate.

The batter is expected to promptly take his place in the batter's box when his turn to bat comes up and is not permitted to exit the box once the pitcher begins his windup or comes to the set position. The batter can request to be granted time by the umpire if the pitcher has not begun his windup or come to the set position. If his request is granted, the batter is then able to exit the box -- but not the dirt area surrounding home plate. He may also exit the box in other select instances, such as after a swing or bunt attempt, a passed ball, a wild pitch or an inside pitch that forces him out of the box. Furthermore, he may exit the box if the pitcher or catcher vacates his respective position, a member of the defensive team requests time or attempts a play on a runner at any base, or an attempted check swing is appealed to a base umpire. Otherwise, the batter is expected to keep at least one foot inside the box throughout his time at bat.

If a batted ball that has not yet been touched by a fielder makes contact with a batter who still has two feet in the batter's box, the ball will be ruled foul. But if the batter has already exited the batter's box before being contacted by a fair ball that has not yet been touched by a fielder, the batter will be called out.

Source: MLB

Batters Faced (BF)

Batters faced is simply a count of the number of total plate appearances against a certain pitcher or team. In a perfect game -- with 27 outs -- a pitcher will record 27 batters faced.

Batters faced can often be used as a reference for in-game strategy. A hurler has gone through the opposing lineup once after facing nine batters. After recording 18 batters faced, he becomes poised to take on the opposing lineup a third time. Not surprisingly, pitchers with high batters faced totals are also the ones who throw the most innings.

Batters faced can be determined by counting the total number of plate appearances -- or by adding runs, runners left on base and total outs.

In A Call

"hitters faced," "batters to the plate," "men to the plate"

Source: MLB

Batting Average (AVG)

One of the oldest and most universal tools to measure a hitter's success at the plate, batting average is determined by dividing a player's hits by his total at-bats for a number between zero (shown as .000) and one (1.000). In recent years, the league-wide batting average has typically hovered around .250.

While batting average is a useful tool for measuring a player's ability at the plate, it isn't all-encompassing. For instance, batting average doesn't take into account the number of times a batter reaches base via walks or hit-by-pitches. And it doesn't take into account hit type (with a double, triple or home run being more valuable than a single).

Batting average can also be applied in evaluating pitchers. In this case, it is called either "opponents' batting average" or "batting average against," and it is determined by dividing the number of hits against a given pitcher by the number of at-bats against him.

BAA is very common in evaluating pitchers -- especially when assessing opponent handed-ness splits. A pitcher cannot have an ERA against left-handed hitters because they are interspersed with righties in lineups. So when a pitcher's ability against hitters from each side of the plate is being compared, it is usually done by using either BAA or OPS-against.

Origin

Batting average was created as a measure to judge the success of a hitter. For one season, in 1887, walks counted as hits as well. But after that season, it was determined that batting average should take into account only a batter's hits -- and not any other methods he used to reach base.

In A Call

"average," as a verb: "he's batting" or "he's hitting"

Source: MLB

Batting Average on Balls in Play (BABIP)

BABIP measures a player's batting average exclusively on balls hit into the field of play, removing outcomes not affected by the opposing defense (namely home runs and strikeouts).

For example, a hitter who goes 2-for-5 with a home run and a strikeout would have a .333 BABIP. He's 1-for-3 on the balls he put in play.

The formula

(H - HR)/(AB - K - HR + SF)

Why it's useful

BABIP can be used to provide some context when evaluating both pitchers and hitters. The league average BABIP is typically around .300. Pitchers who have allowed a high percentage of hits on balls in play will typically regress to the mean, and vice versa. In other words, over time, they'll see fewer (or more) balls in play fall for hits, and therefore experience better (or worse) results in terms of run prevention. The same applies for batters who have seen a high or low percentage of their balls in play drop in for hits.

That said, skill can play a role in BABIP, as some pitchers are adept at generating weak contact, while some hitters excel at producing hard-hit balls. For example, Clayton Kershaw finished the 2019 season with a lifetime .270 BABIP allowed, while Mike Trout ended the campaign with a career .348 BABIP.

Source: MLB

Batting Out of Turn

If a team bats out of turn, the onus is not on the umpires to notify either team of the transgression. The consequences of batting out of turn vary depending on the timing of the appeal.

Appeal made during plate appearance

If the opposing team makes its appeal or the offensive team realizes its error before the incorrect batter's plate appearance has concluded, then the correct batter can take his place at bat while assuming the incorrect batter's count.

Appeal made following plate appearance but before next pitch or attempted play

If the appeal occurs between the conclusion of the incorrect batter's plate appearance but before the next pitch or attempted play, the correct batter is called out. Furthermore, any score or advancement caused by the incorrect batter batting a ball or reaching first base is nullified.

However, scores or advancements are counted if they occur as a result of a stolen base, balk, wild pitch or passed ball during the incorrect batter's plate appearance.

Appeal made following plate appearance and after next pitch or attempted play

If no appeal is made before the next pitch or attempted play following the conclusion of the incorrect batter's plate appearance, the incorrect batter is now considered to have batted in turn and all scores or advancements made during or as a result of his plate appearance are counted. The offensive team continues batting in its designated order from that point and places the skipped batter back into his original lineup spot the next time around.

Source: MLB

Bench Coach

A bench coach is typically considered the right-hand man to his team's manager. Bench coaches assist their managers in decision-making and will sometimes relay scouting information from the team's front office to the club's players.

Many bench coaches go on to become managers, or are former managers. The bench coach typically steps in to act as manager when the regular manager is unavailable (often as a result of being ejected from the game).

Source: MLB

Bequeathed Runners (BQR)

Bequeathed runners represents the number of runners left on base by a pitcher when that pitcher leaves the game. Any bequeathed runner who scores an earned run after a pitcher has left the game will be counted against that pitcher's ERA.

Along with being a pitching metric, bequeathed runners can be an assessment of a manager's philosophy. Some managers try to avoid bringing their relief pitchers into a game with men on base. As a result, those teams usually have lower bequeathed runners totals.

In A Call

"inherited runners" (for the pitcher who is entering the game)

Source: MLB

Bequeathed Runners Scored (BQR-S)

Bequeathed runners scored represents the total number of runs a pitcher is charged with after he leaves the game. Or, put another way, it's the number of runners who come around to score after being left on base when that pitcher exits the game.

There is a key exception, however. If a fielder's choice eliminates one of a departed pitcher's baserunners, and the new baserunner scores, that run will still be charged to the original pitcher and not the second pitcher.

BQR-S can be a good way of assessing how much help a starting pitcher received from his bullpen. If a starting pitcher has a high percentage of his bequeathed runners score, it will adversely affect his ERA./p>

In A Call

"inherited runners who scored" (for the pitcher who is entering the game)

Source: MLB

Blown Save (BS)

A blown save occurs when a relief pitcher enters a game in a save situation, but allows the tying run to score. The run does not have to be charged to that pitcher. If a reliever enters with a man already on third base, and he allows that runner to score the tying run, he is charged with a blown save.

Although many blown saves occur in the ninth inning or later, they aren't limited to the ninth inning. If a pitcher enters in the eighth inning and surrenders the tying run in a save situation, he is given a blown save -- regardless of whether he pitches the ninth. A pitcher can still receive either a win or a loss (or a no-decision) after recording a blown save, depending on the ensuing results.

Blown saves are used as a tool to evaluate the effectiveness of a closer. However, not all blown saves are created equal -- after all, entering with a three-run lead in the ninth and entering with a one-run lead and a man on third in the eighth are both considered save situations. It's important to remember this when assessing closers based on their blown saves.

Origin

Blown saves were introduced as a statistic in 1988 as a counterbalance for the statistic "saves."

In A Call

"saves blown," "saves lost," "blown leads in save situations"

Source: MLB

Bolt

A Bolt is any run where the Sprint Speed (defined as "feet per second in a player's fastest one-second window") of the runner is at least 30 ft/sec.

Players' Bolt totals for each season are displayed on the Sprint Speed leaderboard. It is a cumulative stat, unlike Sprint Speed.

Billy Hamilton finished first or second in Bolts in each of the first four seasons in Statcast history. Trea Turner ranked first in 2018, with 145 Bolts -- 43 more than any other player -- though he ranked fourth on the Sprint Speed leaderboard (min. 10 competitive runs).

Since Statcast was implemented Major League-wide in 2015, the number of Bolts per season typically has been similar to the number of stolen bases. For example, there were 2,377 Bolts and 2,474 steals in 2018.

Source: MLB

Bone Bruise

A bone bruise is a traumatic injury to a bone that is less severe than a bone fracture, causing blood and fluid to build up near the injured bone.

Bones have a cortex, or outer shell, made of interconnected fibers. Calcium fills the spaces between the fibers.If enough of those fibers break during a trauma, a bone fracture will result, but a bone bruise occurs when a smaller portion of the fibers break. This can result in pain, swelling and change in color of the affected area.

Typical recovery time

Bone bruises do not show up on X-rays and must be diagnosed with MRIs. Depending on depth and severity, they may heal in as little as a few weeks or require as long as six months.

Source: MLB

Bullpen Coach

The bullpen coach works with pitchers in a similar capacity to the pitching coach before and after games. During a game, the bullpen coach is in the bullpen with his club's relief pitchers and oversees their warmups, while also offering advice on pitching mechanics and pitch selection.

Source: MLB

Bursitis/Shoulder Bursitis

A bursa is a small, fluid-filled sac that serves to reduce friction between a bone and the surrounding soft tissues such as skin, muscles, ligaments and tendons. There are 160 bursae in the body, with the major bursae located in the large shoulder, hip, elbow and knee joints. Bursitis is the inflammation of a bursa.

In baseball players, shoulder bursitis is common in the subacromial bursa between the rotator cuff tendons and the acromion, or shoulder blade. The subdeltoid bursa, located under the deltoid muscle (the rounded contour at the top of the shoulder), may also become inflamed, but it is less common. Shoulder bursitis can be caused by a trauma, but it is more often an overuse injury caused by repeated minor trauma, such as repetitively throwing a baseball. It is often associated with impingement or tendonitis of the rotator cuff tendons.

Typical recovery time

With rest, mild bursitis can be resolved in 2-3 weeks. Cortisone injections into the bursa sac may reduce inflammation. If the condition becomes chronic, however, the inflamed bursa sac may be surgically removed and, over time, a new one will form in its place. Recovery from surgery is typically 6-8 weeks.

Source: MLB

Bush League

"Bush league" describes something that is below professional standards.

Origin

With "bush" being a synonym for a rural area, non-Major League clubs in small towns were referred to as bush league teams in the early days of baseball. The term has come to be used often outside of baseball.

Source: MLB

Butcher Boy

A "butcher boy" is a batter who squares around to bunt, only to pull the bat back and make a short, downward swing.

Origin

Coined by Hall of Fame manager Casey Stengel, the term was inspired by the motion someone in a butcher shop would use to cleave meat. Stengel ordered the maneuver whenever he needed a ground ball.

Source: MLB

C

Can of Corn

A "can of corn" is a routine fly ball hit to an outfielder.

Origin

When 19th-century clerks at groceries and general stores were looking for an easier way to reach canned goods on high shelves, they started using long, hooked sticks to pull them down. After dropping the cans toward them, they would catch them in their aprons -- just like a fly ball.

Source: MLB

Cape Cod Baseball League

The Cape Cod Baseball League is a prestigious collegiate summer league in Massachusetts that has played host to more than 1,250 future Major Leaguers over the years.

Top college players from across the United States are recruited to play in the CCBL, which was officially sanctioned by the NCAA in 1963 but traces its roots back to the late 1800s.

The CCBL currently features 10 teams: The Bourne Braves, Cotuit Kettleers, Falmouth Commodores, Hyannis Harbor Hawks, Wareham Gatemen, Brewster Whitecaps, Chatham Anglers, Harwich Mariners, Orleans Firebirds and Yarmouth-Dennis Red Sox.

The CCBL is notable for its use of wood bats, which were implemented in 1985. This is in contrast to the aluminum bats used by the NCAA.

Five former CCBL players have been inducted into the National Baseball Hall of Fame: Jeff Bagwell, Craig Biggio, Frank Thomas, Carlton Fisk and Pie Traynor.

Source: MLB

Catcher

The catcher crouches directly behind home plate and is primarily responsible for receiving all of a pitcher's pitches.

Catchers have many duties on defense. Primarily, they are responsible for catching all pitches thrown by their teams' pitchers, often suggesting pitch selection by way of pre-pitch hand signals displayed between their legs and out of sight from the opposing team. Catchers are also asked to throw to second base and third base in order to prevent runners from stealing bags. Additionally, catchers block pitches thrown into the dirt in front of home plate and "frame" pitches close to the strike zone by slightly moving their catcher's mitts back toward the strike zone after catching pitches.

Catchers play a psychological role, too, taking the occasional trip to the mound to calm a pitcher down or offer advice when he is struggling.

Source: MLB

Catcher Framing

Catcher framing is the art of a catcher receiving a pitch in a way that makes it more likely for an umpire to call it a strike -- whether that's turning a borderline ball into a strike, or not losing a strike to a ball due to poor framing. The effects of a single pitch can be huge; in 2019, hitters had an .858 OPS after a 1-0 count, but just a .631 OPS after an 0-1 count.

Statcast's catcher framing numbers are primarily based on the edges of the plate (or the "Shadow Zone" in this image), the area that is the width of two baseballs (one inside the zone, one outside) all around the edges of the strike zone. Statcast's catcher framing is adjusted both for park and the pitcher. Read more about catcher framing.

The numbers on the leaderboard are expressed in several different ways:

• Strike rate: Percentage of non-swings on the edges of the zone converted into called strikes. In 2019, Austin Hedges led with 54.1%, and Isiah Kiner-Falefa was at the bottom with 42.3%. The MLB average was 48.1%.
• Runs from Extra Strikes: Converts strikes to runs saved on a .125 run/strike basis. In 2019, Hedges had +20 at the top, and James McCann had -16 at the bottom.
• Zone breakdowns: Allow the strike rate to be expressed in eight different areas around the strike zone, as shown here.

In A Call

"In 2019, Austin Hedges converted 54 percent of takes into strikes on the edges of the zone, the best rate of any catcher in baseball."

Source: MLB

Catcher Interference

The batter is awarded first base if the catcher (or any other fielder) interferes with him at any point during a pitch.

If first base was occupied at the time of the pitch, the runner who held the base is permitted to move up one base. This also applies if first and second base were occupied or the bases were loaded at the time of the pitch.

If first base had been empty at the time of the pitch, no additional runners are permitted to advance.

When catcher interference occurs, the umpire will allow the play to progress because the outcome of the play may be more desirable than the interference. In that case, the offensive manager can elect to accept the outcome of the play over the interference.

Source: MLB

Caught Stealing (CS)

A caught stealing occurs when a runner attempts to steal but is tagged out before reaching second base, third base or home plate. This typically happens after a pitch, when a catcher throws the ball to the fielder at the base before the runner reaches it. But it can also happen before a pitch, typically when a pitcher throws the ball to first base for a pickoff attempt but the batter has already left for second.

Many different factors go into a caught stealing. Namely: a pitcher's quick release to home plate, a catcher's quick transfer and throw, a good tag by the fielder receiving the ball and a poor jump -- or slow first step -- by the baserunner.

If a runner is thrown out trying to advance on a wild pitch or a passed ball, this does not count as a caught stealing. Similarly, a runner who is picked off while diving back to a base has not been "caught stealing" because he never attempted to steal in the first place. If a batter steals a base safely but is tagged when he comes off the base before fully gaining his balance, it still counts as a caught stealing, because he was never established on the base.

Baseball's caught-stealing leaders are typically some of the fastest players in the game, as such players attempt to steal the most bases.

When a catcher gets an assist on a caught stealing, he is awarded a catcher caught stealing (CCS). He is also awarded a CCS if the recipient drops his throw for an error and the official scorer judges that the runner would have been out had the ball been caught. However, when a runner is thrown out trying to advance on a wild pitch or a passed ball, a catcher caught stealing is not awarded.

In A Call

"nailed," "thrown out," "nabbed," "hosed"

Source: MLB

Cellar

The "cellar" refers to last place.

Origin

Cellar is another word for basement, which is the lowest floor in a building or a house. Thus, the team in last place -- the lowest spot in a division or a league -- is said to be in the cellar.

Source: MLB

Center Fielder

The center fielder covers the middle portion of the outfield (when viewing the field from home plate).

Range is imperative for a center fielder, as he has more ground to cover than either of the corner outfielders. Center fielders ideally will also possess strong throwing arms, as they often are required to throw to home, third and second in an effort to prevent baserunners from advancing.

The center fielder is considered the "captain" of the outfield and typically will take precedence over a corner outfielder if the two are attempting to field the same ball. Center fielders will often call off corner outfielders by yelling "I got it" in such situations.

Source: MLB

Changeup (CH)

A changeup is one of the slowest pitches thrown in baseball, and it is predicated on deception.

The changeup is a common off-speed pitch, and almost every starting pitcher owns a changeup as part of his arsenal. (A larger number of relief pitchers do not, because they typically only face hitters once and therefore have less of a need for deception.) A good changeup will cause a hitter to start his swing well before the pitch arrives, resulting in either a swing and miss or very weak contact. But when a hitter is able to identify the changeup, the pitch is among the easiest to hit because of its low velocity.

Grip

There are several different grips that pitchers use for a changeup, but the common theme is that the ball rests farther back in the hand -- even, in some cases, in the palm. They are thrown with a nearly identical motion to that of a fastball, causing the intended deception.

Origin

The changeup has been around for as long as the game has existed. In the early days of baseball, when breaking balls were considered unfair and deceitful, most pitchers settled for throwing exclusively straight pitches, and a few of them mixed speeds. Thus, the slower pitches in that era could be considered the game's first changeups.

In A Call

"change," "change of pace," "off-speed," "slowball," "the dreaded equalizer"

Source: MLB

Chin Music

"Chin music" refers to a pitch that is thrown high and inside, near a batter's head.

Source: MLB

Closer

Closers stand on the pitching mound, which is located in the center of the infield and 60 feet, six inches away from home plate.

A closer is often considered the best relief pitcher that a club has in its bullpen. Closers are most often deployed for the final inning of a game when a narrow lead -- three runs or less -- needs to be protected. Closers almost always excel against both right- and left-handed batters and are more often than not capable of striking out batters at high rates. Most closers are right-handed, although there are typically a few left-handed closers in baseball each season.

On offense: Closers receive even fewer at-bats than the standard relief pitcher, as they appear only late in games. If a closer's spot comes up in the batting order, the manager will often pinch-hit for the closer. Most closers go the entire season without an at-bat. For example, Aroldis Chapman tallied just two at-bats over the first six seasons of his Major League career.

Source: MLB

Club Option

A club option is an optional year at the end of the contract which may be guaranteed at the discretion of the club. In most instances, the option comes with a buyout that represents a fraction of the option value. If the player is injured or performs on a level that the club believes the option value to be too expensive, the club will typically pay the buyout and decline the option. In most cases, this results in the player being eligible for free agency. However, if a player signed a contract that turned one of his arbitration-eligible seasons into an option season, the option can be declined with the player then entering the arbitration process instead.

Should the club exercise the option, the player is considered signed for the following season at that option's value. Contracts can contain multiple option years.

Examples

Following the 2016 season, the Kansas City Royals exercised their club option on Wade Davis before trading him to the Chicago Cubs in December 2016. The option was part of the contract extension Davis had signed with the Tampa Bay Rays in March 2011, guaranteeing his salary for the 2011-14 seasons and including club options for 2015, 2016 and 2017. Davis was dealt to the Royals as part of a December 2012 trade and played for the team from 2013-16, with Kansas City picking up his club option for each of the latter two years in that span.

Meanwhile, the Nationals picked up Gio Gonzalez's club option but declined Yusmeiro Petit's in November 2016. Petit subsequently signed a Minor League contract with the Angels and made the team's 2017 Opening Day roster.

Source: MLB

Coach Interference

If a base coach interferes with a thrown ball, the runner will be ruled out. But if a thrown ball accidentally touches the base coach, the ball is alive and in play. Coaches must respect the fielder's right of way to make a play on a batted or thrown ball.

Base coaches can also be called for interference if the umpire determines that they physically assisted a runner -- by grabbing or holding said runner -- from leaving or returning to first or third base. Moreover, base coaches are not permitted to leave their boxes and act in any manner intended to draw a throw by a fielder.

Source: MLB

Collisions at Home Plate

The baserunner is not allowed to deviate from his direct path to initiate contact with the catcher (or any player covering the plate). Runners are considered to be in violation of this rule if they collide with the catcher in cases where a slide could have been used to avoid the collision. If the umpire determines that the runner violated this rule, the runner shall be ruled out and the ball is dead. The other runners must return to the last base they had touched at the time of the collision.

The catcher is not permitted to block the runner's path to the plate unless he is in possession of the ball, though blocking the path of the runner in a legitimate attempt to receive a throw is not considered a violation. The runner can be ruled safe if the umpire determines the catcher violated this rule. But per a September 2014 memorandum to the rule, the runner may still be called out if he was clearly beaten by the throw. Backstops are not subject to this rule on force plays.

When receiving a throw, catchers will often provide a sliding lane into home plate for the runner to lower the possibility that they will be called for violating the rule. Likewise, runners can lower their chances of being called for a violation by sliding in the given lane.

History of the rule

In an attempt to place greater emphasis on player safety, the rule was adopted on an experimental basis for the 2014 season. The change was made partially in response to a May 2011 collision at home plate that saw star catcher Buster Posey suffer a season-ending ankle injury. MLB clarified the rule with the September 2014 memorandum.

Source: MLB

Competitive Balance Draft Picks

Competitive Balance Draft picks were implemented in the 2012-16 Collective Bargaining Agreement. The process to assign picks was amended in the 2017-21 Collective Bargaining Agreement.

The 10 lowest-revenue clubs and the clubs from the 10 smallest markets are eligible to receive a Competitive Balance pick (fewer than 20 clubs are in the mix each year, as some clubs qualify under both criteria). All eligible teams are assigned a pick, either in Competitive Balance Round A or Round B. Round A falls between the first and second rounds of the Rule 4 draft, while Round B comes between the second and third.

Under the 2017-21 CBA, six clubs will be awarded picks in Round A based on a formula that considers winning percentage and revenue. Those six teams will pick in Round A in 2017, 2019 and 2021. The remaining teams -- estimated to be between six and eight -- will pick in Round B in those years. The groups of teams, which will not change for the duration of the 2017-21 CBA, will switch picking in Round A and B in alternating years based on their initial assignment of round in 2017.

Clubs drafting in the Competitive Balance Rounds also receive more international bonus pool money than the minimum of $4.75 million. Those drafting in Competitive Balance Round A will receive $5.25 million, while those in Competitive Balance Round B will get $5.75 million.

Unlike other Draft picks, Competitive Balance Draft picks can be traded. However, they cannot be dealt simply in exchange for cash, and can be traded only by the club to which it was awarded. In other words, the picks may be traded no more than once.

History of the rule

Under the 2012-16 Collective Bargaining Agreement, the 10 lowest-revenue clubs and the clubs from the 10 smallest markets were entered into a lottery. The first six clubs selected in the lottery received a Draft selection in Competitive Balance Round A, while the next six clubs selected received a pick in Competitive Balance Round B.

Example

On June 1, 2014, the Marlins traded their Competitive Balance Round A selection to the Pirates in exchange for right-hander Bryan Morris. The Pirates received the 39th pick in the Draft that followed just days later.

Source: MLB

Competitive Balance Tax

Each year, clubs that exceed a predetermined payroll threshold are subject to a Competitive Balance Tax -- which is commonly referred to as a "luxury tax." Those who carry payrolls above that threshold are taxed on each dollar above the threshold, with the tax rate increasing based on the number of consecutive years a club has exceeded the threshold.

A team's Competitive Balance Tax figure is determined using the average annual value of each player's contract on the 40-man roster, plus any additional player benefits. Every team's final CBT figure is calculated at the end of each season. (Note: If a player signs a contract extension that doesn't kick in until a later season, his AAV for the purposes of the CBT doesn't change until the new deal begins.)

The threshold was $189 million from 2014-16, but the following increases were put in place per the 2017-21 Collective Bargaining Agreement:

2017: $195 million*

2018: $197 million

2019: $206 million

2020: $208 million

2021: $210 million

*For 2017 only, clubs that exceeded the threshold paid the average between what their luxury tax was under the 2017-21 Collective Bargaining Agreement rules and what it would have been per the previous CBA.

A club exceeding the Competitive Balance Tax threshold for the first time must pay a 20 percent tax on all overages. A club exceeding the threshold for a second consecutive season will see that figure rise to 30 percent, and three or more straight seasons of exceeding the threshold comes with a 50 percent luxury tax. If a club dips below the luxury tax threshold for a season, the penalty level is reset. So, a club that exceeds the threshold for two straight seasons but then drops below that level would be back at 20 percent the next time it exceeds the threshold.

Clubs that exceed the threshold by $20 million to $40 million are also subject to a 12 percent surtax. Meanwhile, those who exceed it by more than $40 million are taxed at a 42.5 percent rate the first time and a 45 percent rate if they exceed it by more than $40 million again the following year(s).

Beginning in 2018, clubs that are $40 million or more above the threshold shall have their highest selection in the next Rule 4 Draft moved back 10 places unless the pick falls in the top six. In that case, the team will have its second-highest selection moved back 10 places instead.

History of the rule

The 2012-16 Collective Bargaining Agreement required clubs to pay a 17.5 percent luxury tax for first-time overages. Clubs that exceeded the threshold for two, three and four consecutive years were taxed at 30, 40 and 50 percent rates, respectively.

Example

In 2019, the Cubs, Red Sox and Yankees exceeded the Competitive Balance Tax threshold. The Cubs and Yankees exceeded the threshold again in 2020, so they incurred a steeper tax rate than the previous year. The Astros, meanwhile, were first-time CBT payors in 2020.

Source: MLB

Complete Game (CG)

A pitcher earns a complete game if he pitches the entire game for his team regardless of how long it lasts. If the game is shortened by rain or if it lasts into extra innings, it counts as a complete game if the pitcher was the only pitcher to record an appearance for his team.

Complete games are considered valuable in baseball for a variety of reasons. First of all, if a pitcher hurls a complete game, it generally means he pitched well -- usually well enough for a victory and sometimes even well enough for a shutout (a complete game with no runs allowed). But complete games are also important because they give the bullpen an entire day of rest, keeping it fresh for the future.

Typically, the league leaders in complete games are pitchers who can keep their pitch counts low and avoid walks (and sometimes strikeouts, too, because strikeouts typically require more pitches to achieve than other types of outs). It takes a major effort for a pitcher to toss a complete game, as fatigue generally sets in during the later innings.

As bullpens have grown in importance over the past few decades, complete games have become increasingly rare.

In A Call

"goes the distance"

Source: MLB

Contract Renewal

Players who haven't signed a long-term contract extension or accrued the MLB service time necessary to be eligible for salary arbitration can have their contracts renewed by their clubs as one-year deals for the coming season.

These pre-arbitration players can negotiate their salaries but have little leverage, as clubs can choose to renew a contract for the Major League minimum if they cannot come to an agreement with the player. Of course, clubs may choose to sign their pre-arbitration players to one-year deals for more than the Major League minimum to build good will for future negotiations, but they are under no obligation to do so.

Clubs cannot reduce players' salaries by more than 20 percent of what they earned in the previous MLB season -- including a player's base salary and additional payments such as performance bonuses, signing bonuses and deferred compensation -- or 30 percent of what they earned two seasons prior, per the Maximum Salary Reduction clause in the Collective Bargaining Agreement.

Examples

The Red Sox were not able to come to an agreement with Mookie Betts on a salary for the 2017 season, so they renewed his contract for $950,000 -- up from the $566,000 he earned in 2016. The Astros renewed Alex Bregman's contract for the 2018 season, giving the third baseman $599,000 after he earned $539,400 in 2017.

Conversely, the Cubs and Kris Bryant came to an agreement on a $1.05 million contract for the 2017 season in Bryant's last year before salary arbitration, setting a record for the largest one-year deal ever given to a pre-arbitration player.

Source: MLB

Contract Tendered

To "tender" a contract to a player is to agree to give a contract for the upcoming season to a player who is under club control. Players on the 40-man roster with fewer than six years of Major League service time must be tendered contracts or they will be considered "non-tendered" and immediately made eligible for free agency. Contracts must be tendered to both arbitration-eligible and pre-arbitration players, though the latter group has no say in its forthcoming salary.

Tendering a contract to an arbitration-eligible player does not mean that the two sides set a specific salary, but rather that they agree to come to terms on a salary between the date of the tender and late February. If the two sides cannot come to terms on a salary or multi-year deal, an arbitration hearing will be held and a panel of arbitrators will determine his salary. The offseason deadline for clubs to tender contracts to eligible players typically falls in early December.

Example

Having accrued more than five but fewer than six years of service time, Brandon Moss was eligible for one more round of arbitration following the 2015 season. The Cardinals tendered a contract to Moss and ultimately agreed to a one-year, $8.25 million deal with him to avoid arbitration.

Source: MLB

Curveball (CU)

A curveball is a breaking pitch that has more movement than just about any other pitch. It is thrown slower and with more overall break than a slider, and it is used to keep hitters off-balance. When executed correctly by a pitcher, a batter expecting a fastball will swing too early and over the top of the curveball.

Most professional pitchers possess either a curveball or a slider -- and some possess both breaking pitches. Having a breaking pitch, like a curveball, is an essential component to a professional starter's arsenal, because it keeps the hitter off-balance and unable to commit to gearing up exclusively for a fastball.

The curveball has been one of the most commonly used pitches throughout baseball history, and the universally accepted signal for a curveball is a catcher putting down two fingers.

The pitch is so well known in American culture that the phrase "throw a curveball" has emerged as an idiom. Like the goal of pitchers when throwing the pitch, the idiom "to throw a curve" means to trick someone with something unexpected.

Grip

A curveball can be thrown with a number of different grips. Some pitchers possess curveballs with a sweeping, sideways trajectory, while other curveballs break straight downward. (These are known as 12-to-6 curveballs.)

The slider and the curveball are sometimes confused because they generally have the same purpose -- to deceive the hitter with spin and movement away from a pitcher's arm-side. (When a pitch seems to toe the line between the two, it is referred to in slang as a "slurve.")

Like a slider, a curveball is thrown by a pitcher with a wrist snap and spin. A curveball that doesn't break as much as a pitcher hopes is referred to as a "hanging curve" or a "hanger" and is much easier for the batter to hit because of its straight trajectory and sub-fastball velocity.

Origin

When pitchers first began throwing the curveball in the mid-1800s, it was considered deceptive and dishonest, but because it could not be outlawed with a specific rule, the pitch persisted and eventually became a staple of the game. It's often debated as to who threw the first curveball, with most historians giving the accolades to Hall of Famer Candy Cummings. The first well known documentation of the pitch came in the New York Clipper. In 1869, the newspaper described Phonney Martin as an "extremely hard pitcher to hit for the ball never comes in a straight line, but in a tantalizing curve."

In A Call
"curve," "hook," "deuce," "breaking ball," "slow breaking ball," "bender," "number two," "Uncle Charlie"

Source: MLB

Cutter (FC)

A cutter is a version of the fastball, designed to move slightly away from the pitcher's arm-side as it reaches home plate. Cutters are not thrown by a large portion of Major League pitchers, but for some of the pitchers who possess a cutter, it is one of their primary pitches.

A pitcher with an effective cutter can break many bats. When thrown from a right-handed pitcher to a left-handed hitter, or a lefty pitcher to a righty hitter, a cutter will quickly move in toward a hitter's hands. If the hitter swings, he often hits the ball on the smaller part -- or handle -- of the bat, causing it to break.

In rare cases, switch-hitters have been known to bat from the same side as the pitcher's throwing arm when that pitcher throws primarily cutters. (Typically, a switch-hitter will hit from the opposite side of a pitcher's throwing arm.) This is because the unique movement on the cutter causes hitters to get jammed when facing a pitcher of the opposite handedness.

Grip

The key to a cutter is deception. Batters are accustomed to facing either straight four-seam fastballs or two-seam fastballs that break toward the pitcher's arm side. The cutter breaks in the opposite direction of a two-seamer, and it does so very late in its journey to home plate. This movement is designed to make sure the hitter isn't able to hit the pitch squarely.

Origin

The cut fastball has been thrown for more than 50 years, but it was made famous by Yankees closer Mariano Rivera, who threw the pitch almost exclusively. Rivera's cutter had so much late movement, it gained fame for the sheer number of left-handed hitters' bats that it broke.

In A Call

"cut fastball"

Source: MLB

D

Dead Ball

A dead ball is a ball that is out of play. The ruling of a dead ball halts the game and no plays can legally occur until the umpire resumes the game, though baserunners can advance as the result of acts that occurred while the ball was live. Dead balls are frequent occurrences during a game, and the dead-ball period typically does not last long before the ball is put back into play.

Dead balls most frequently occur when a batted ball becomes a foul ball or a fair ball is hit out of the playing field. Other common instances in which the ball is ruled dead include a batter being hit by a pitch, a balk, an illegal collision at home plate, obstruction of a baserunner, interference with a fielder's right of way, spectator interference, a batter or runner being granted time out by the umpire and a fair batted ball striking an umpire or runner.

If a fair ball gets lodged in the outfield wall padding -- or the ivy, in the case of Wrigley Field -- it is a ground-rule double. On all ground-rule doubles, the ball is dead, the batter-runner goes to second and all additional runners are permitted to move up two bases from the one they occupied at the time of the pitch.

Source: MLB

Defensive Efficiency Ratio (DER)

Defensive Efficiency Ratio is a statistic used to evaluate team defense by finding out the rate of times batters reach base on balls put in play. Basically, for every ball hit into the field of play, how likely is the defense to convert that into an out?

The formula for Defensive Efficiency Ratio is: 1 - ((H + ROE - HR) / (PA - BB - SO - HBP - HR)).

In A Call

"defensive out percentage"

Source: MLB

Defensive Runs Saved (DRS)

DRS quantifies a player's entire defensive performance by attempting to measure how many runs a defender saved. It takes into account errors, range, outfield arm and double-play ability. It differs only slightly from UZR (Ultimate Zone Rating) in its formula, but the concept is the same.

The formula

DRS uses Baseball Info Solutions data to chart where each ball is hit. Say, for instance, a center fielder sprints to make a nice catch on a fly ball. Then, say data from BIS tells us that similar fly balls get caught 60 percent of the time. That center fielder gains, essentially, 0.4 bonus points for difficulty. If he can't make the play, he loses 0.6 points. At the end of the day, that player's overall score gets adjusted to the league average -- and then that score gets adjusted for how many runs the once-adjusted score is worth.

Why it's useful

Like Ultimate Zone Rating (UZR), DRS provides a more in depth way to evaluate fielders than some traditional defensive stats do.

Source: MLB

Designate for Assignment (DFA)

When a player's contract is designated for assignment -- often abbreviated "DFA" -- that player is immediately removed from his club's 40-man roster. Within seven days of the transaction (had been 10 days under the 2012-16 Collective Bargaining Agreement), the player can either be traded or placed on irrevocable outright waivers.

If the player is claimed off said waivers by another club, he is immediately added to that team's 40-man roster, at which point he can be optioned to the Minor Leagues (if he has Minor League options remaining) or assigned to his new team's 26-man roster (it was 25, prior to 2020). If the player clears waivers, he may be sent outright to the Minor Leagues or released. Players with more than three years of Major League service time or who have been previously outrighted may reject the outright assignment in favor of free agency.

Clubs may utilize this option to clear a spot on the 40-man roster -- typically with the intention of adding a newly acquired player (via trade or free agency), a Minor Leaguer or a player being activated from the 60-day injured list.

Source: MLB

Designated Hitter

The designated hitter -- or "DH" -- is a player who bats in place of the pitcher. The pitcher still handles his regular duties when his team is on defense, so the designated hitter does not play in the field.

The rule was adopted by the American League in 1973, while pitchers continued to hit in games played at National League parks. That changed in 2020, with MLB instituting a universal DH for one season as part of its health and safety protocols during the COVID-19 pandemic. It's possible the NL could revert to its traditional rules in 2021.

Clubs utilize the DH position in several ways, with some employing a full-time DH and others using it as a means to provide one of their other regular players with a partial day of rest. The position can be beneficial to aging or injury-prone players who are no longer capable of playing defense on a regular basis but can still offer value at the plate. Additionally, if teams have two strong hitters who play the same defensive position, they can use the DH spot to keep both players in the lineup.

Because the designated hitter position does not provide a defensive component, the DH typically is expected to produce in above-average fashion on offense.

 

Source: MLB

Designated Hitter Rule

The designated hitter rule allows teams to use another player to bat in place of the pitcher. Because the pitcher is still part of the team's nine defensive players, the designated hitter -- or "DH" -- does not take the field on defense.

The rule was adopted by the American League in 1973, while pitchers continued to hit in games played at National League parks. That changed in 2020, with MLB instituting a universal DH for one season as part of its health and safety protocols during the COVID-19 pandemic. It's possible the NL could revert to its traditional rules in 2021.

The DH must be selected prior to the game, and that selected hitter must come to bat at least one time -- unless the opposing team changes pitchers prior to that point. A team that chooses not to select a DH prior to a game is barred from using a DH for the rest of that game. A player who enters the game in place of the DH -- either as a pinch-hitter or a pinch-runner -- becomes the DH in his team's lineup thereafter.

If a player serving as the DH is later used on defense, he continues to bat in his same lineup spot. But for the rest of the game, his team cannot use a DH to bat in place of the pitcher. A team is also barred from using a DH for the rest of the game if the pitcher moves from the mound to another defensive position, a player pinch-hits for any other player and then becomes the pitcher, or the current pitcher pinch-hits or pinch-runs for the DH.

History of the rule

The designated hitter rule was adopted by the AL in 1973. Prior to 2020, pitchers were required to bat in all NL games and Interleague games in which the NL team was the designated home team.

The DH was not used in the World Series from 1973-75, then was used by both World Series teams during even-numbered years from '76-85. The practice of playing each game by the rules of the designated home team's league began in the 1986 World Series.

Source: MLB

Distance Covered (DCOV)

Distance Covered represents the total distance covered by a defender from the time the bat makes contact with the ball until the moment he fields it. This metric only takes into account the route actually traveled by the fielder -- NOT the direct route from the fielder's starting position to the ball. (In fact, if you divide a player's optimal route to the ball by his Distance Covered, you get another Statcast metric called "Route Efficiency.")

Distance Covered can be a fascinating metric, but only when given proper context. For instance, if an outfielder covers 100 feet to make a catch -- it's far more impressive if he does so in four seconds than if the ball hangs in the air long enough for him to do so in seven seconds.

In A Call

"range covered," "ground covered"

Source: MLB

Doctoring the Baseball

No player is permitted to intentionally damage, deface or discolor the baseball by rubbing it with any type of foreign item or substance, including dirt or saliva. Failure to follow this rule will result in an ejection and an automatic 10-game suspension.

The pitcher is allowed to rub the ball between his bare hands but cannot spit on the ball, his hands or his glove. Also, pitchers are not allowed to rub the ball on their clothes, glove or other body parts besides their hands, nor are they permitted to pitch with an attachment such as a bandage, tape or bracelet on either hand or wrist.

While in contact with the pitching rubber, the pitcher is not allowed to touch his mouth or lips at all. He can touch his mouth or lips when in the 18-foot circle surrounding the pitching rubber, but he is not permitted to then touch the baseball or the pitching rubber without first wiping his pitching hand dry. The pitcher shall be issued a warning the first time he violates this rule and then the umpire shall call an automatic ball for each subsequent violation. The pitcher may be allowed to blow on his pitching hand in a game played in cold weather, provided both managers agree to that exception prior to the start of the game.

History of the rule

Pitches utilizing foreign substances, such as the spitball, were outlawed in 1920, but teams were allowed to designate up to two pitchers who could legally use the spitball during the 1920 season. Following that campaign, Major League Baseball designated 17 pitchers as legal spitballers who were permitted to use the spitball for the remainder of their careers. The spitball hasn't been legally used since Burleigh Grimes retired in 1934.

Source: MLB

Double (2B)

A batter is credited with a double when he hits the ball into play and reaches second base without the help of an intervening error or attempt to put out another baserunner.

Doubles are typically hit either into a gap, down the lines or off the outfield wall. They often score speedier runners from first base -- except for in the instance of a ground-rule double, where the ball bounces into the stands and all baserunners, including the batter, are awarded two bases.

Late in games, teams often employ a "no-doubles defense" when they have the lead, where outfielders play very deep in an effort to prevent extra-base hits.

In A Call

"two-bagger," "two-base hit," "extra bases"

Source: MLB

Double Play (DP)

A double play occurs when two offensive players are ruled out within the same play. It's often referred to as "a pitcher's best friend" because it's twice as helpful toward his cause as any given out.

Double plays can be made in any number of ways, but the most common form is on a ground ball with a runner on first. In this case, the defense typically throws the ball to second base to get the first out before throwing the ball to first base for the second out.

A double play can be recorded on a flyout if a fielder throws out a runner who strayed off his base or was trying to advance. Double plays also don't necessarily need to feature a force out at second. If the defense gets the out at first base, then tags another runner out on the bases, that counts as a double play as well.

Pitchers who record the highest number of double plays typically induce a high frequency of ground balls. And defenses that are adept at turning double plays generally have two very good middle infielders who are skilled at both starting the double play and at making a quick catch and throw from second base.

In A Call

"turned two," "doubled up," "twin killing," "pitcher's best friend"

Source: MLB

E

Earned Run (ER)

An earned run is any run that scores against a pitcher without the benefit of an error or a passed ball. Often, it is the judgment of the official scorer as to whether a specific run would've scored without the defensive mishap. If a pitcher exits a game with runners on base, any earned runs scored by those runners will count against him.

Earned runs is the key counting statistic used in ERA, the most widely accepted barometer of a pitcher's success.

If there are no errors or passed balls in a given inning or game, all the runs in that inning or game are earned runs.

In A Call

"He allowed X earned"

Source: MLB

Earned Run Average (ERA)

Earned run average represents the number of earned runs a pitcher allows per nine innings -- with earned runs being any runs that scored without the aid of an error or a passed ball. ERA is the most commonly accepted statistical tool for evaluating pitchers.

The formula for finding ERA is: 9 x earned runs / innings pitched. If a pitcher exits a game with runners on base, any earned runs scored by those runners will count against him.

ERA should be an ideal evaluation of pitchers. The goal of pitching is to prevent runs from scoring, and ERA tells us basically how well a pitcher does that. How many runs does he allow, on average, that are his fault in a given game?

But there are a few flaws with ERA, because so many different factors can affect it. While defensive mistakes are taken into account, great defensive plays are not. So a pitcher with an average defense is at a disadvantage to a pitcher with a great defense. It's also hard to evaluate ERA across the two leagues in Major League Baseball, because the absence of a designated hitter in the National League tends to keep pitchers' ERAs lower. Even the ballpark in which a pitcher pitches can affect a pitcher's ERA because certain stadiums are more conducive to run scoring.

Still, ERA is a useful tool for measuring a starting pitcher's success. However, it's not quite as effective in measuring relief pitchers, who often pitch only fractions of an inning -- sometimes leaving their ERA in the hands of other relievers. Even relief pitchers who pitch a full inning tend to exert all their energy on those three outs, instead of spreading it out over the course of a game. This means relievers generally have lower ERAs than starting pitchers.

Origin

Statistician and writer Henry Chadwick gets credit for inventing ERA in the mid-to-late 19th century. His thinking was that win-loss record simply didn't go far enough in determining the mark of a good pitcher. The statistic caught on in the 20th century, when relief pitchers became more prevalent. This made win-loss records even less reliable, because a starting pitcher could pitch a great game and not receive credit in the win column if his bullpen didn't preserve the victory.

In A Call

ERA is generally referred to directly after an announcer gives a pitcher's win total. Something like: "He's 2-0 with a 3.33 ERA."

Source: MLB

Eephus (EP)

The eephus is one of the rarest pitches thrown in baseball, and it is known for its exceptionally low speed and ability to catch a hitter off guard.

Typically, an eephus is thrown very high in the air, resembling the trajectory of a slow-pitch softball pitch. Hitters, expecting a fastball that's nearly twice the velocity of the eephus, can get over-zealous and swing too early and hard. But for a hitter who is able to keep his weight back and put a normal swing on the pitch, it is the easiest pitch to hit in baseball -- one without unexpected movement or excessive velocity.

Origin

Pirates pitcher Rip Sewell was the first pitcher to throw the eephus pitch regularly -- although, at the time, the pitch hadn't yet been named. Sewell's teammate Maurice Van Robays took care of that. He concocted the name "eephus" and when asked why, he responded by saying, "Eephus ain't nothing, and that's a nothing pitch." In Hebrew, the word "efes" can be loosely translated into "nothing," and the word "eephus" undoubtedly stems from that.

In A Call

"eephus pitch," "slowball," "overhand softball pitch," "folly floater," "LaLob," "spaceball"

Source: MLB

Error (E)

A fielder is given an error if, in the judgment of the official scorer, he fails to convert an out on a play that an average fielder should have made. Fielders can also be given errors if they make a poor play that allows one or more runners to advance on the bases. A batter does not necessarily need to reach base for a fielder to be given an error. If he drops a foul ball that extends an at-bat, that fielder can also be assessed an error.

Defensive errors are a factor in some statistical equations. For instance, batters do not receive RBIs for any runs that would not have scored without the help of an error. And pitchers are not assessed any earned runs for runs that would not have scored without the error.

The league leaders in errors are typically shortstops and third basemen, who have to deal with a wide array of tricky ground balls and tough throws across the diamond. There is no classification of errors either. So a shortstop who makes a nice play on a ball but throws it away, allowing the batter to advance to second, is given an error, much in the same way an outfielder would be if he dropped an easy fly ball.

In A Call

"blunder," "booted it," "miscue," "mishap," "E"

Source: MLB

Exit Velocity (EV)

Exit Velocity measures the speed of the baseball as it comes off the bat, immediately after a batter makes contact. This is tracked for all Batted Ball Events -- outs, hits and errors.

Attaining a high Exit Velocity is one of a hitter's primary goals. A hard-hit ball won't always have a positive result, but the defense has less time to react, so the batter's chances of reaching base are higher.

For this very reason, Exit Velocity can also be used to evaluate pitchers (known as "Exit Velocity Against"). The game's best pitchers -- who naturally throw the highest quality pitches -- generally rank among the league leaders at limiting hard contact.

Average Exit Velocity (aEV) is calculated by dividing the sum of all Exit Velocities by all Batted Ball Events.

Fantasy advantage

Hitting the ball hard (or limiting hard contact, in the case of pitchers) is skill-based and therefore considered at least somewhat predictive of future performance. If a player is struggling statistically but registering impressive Exit Velocity readings, he may be a candidate to bounce back in the near future. For example: Say Player A hit .200 in April but ranked among the league leaders in average Exit Velocity; a wise fantasy owner could look at Player A's average Exit Velocity and surmise that he will eventually regress toward his career statistical averages. The same exercise can be done with players who are exceeding expectations; if a hitter's Exit Velocity is low, he is less likely to maintain his torrid pace at the plate.

In A Call

"exit velo"

Source: MLB

Expected Batting Average (xBA)

Expected Batting Average (xBA) is a Statcast metric that measures the likelihood that a batted ball will become a hit.

Each batted ball is assigned an xBA based on how often comparable balls -- in terms of exit velocity, launch angle and, on certain types of batted balls, Sprint Speed -- have become hits since Statcast was implemented Major League wide in 2015. (As of January 2019, xBA now factors in a batter's seasonal Sprint Speed on "topped" or weakly hit" balls).

For example, a line drive to the outfield with an xBA of .700 is given that figure because balls with a similar exit velocity and launch angle have become hits seven out of 10 times.

Knowing the expected outcomes of each individual batted ball from a particular player over the course of a season allows for the formation of said player's Expected Batting Average on balls in play. Real-world strikeout totals are then added in, resulting in a player's seasonal Expected Batting Average based on the quality of contact, instead of the actual outcomes. Likewise, this exercise can be done for pitchers to get their Expected Batting Average against.

Hit Probability

Expected Batting Average is derived from Hit Probability, a depreciated metric that was used in 2017-18 and also measured the likelihood that a batted ball would become a hit. The difference is that Hit Probability was represented as a percentage, while xBA presents numbers on a batting-average scale.

Beginning with 2019, the name Hit Probability has been retired in favor of Expected Batting Average.

Why it's useful

Expected Batting Average is more indicative of a player's skill than regular batting average, as xBA removes defense from the equation. Hitters, and likewise pitchers, are able to influence exit velocity and launch angle but have no control over what happens to a batted ball once it is put into play.

Source: MLB

Expected ERA (xERA)

Expected ERA, or xERA, is a simple 1:1 translation of Expected Weighted On-Base Average (xwOBA), converted to the ERA scale. xwOBA takes into account the amount of contact (strikeouts, walks, hit by pitch) and the quality of that contact (exit velocity and launch angle), in an attempt to credit the pitcher or hitter for the moment of contact, not for what might happen to that contact thanks to other factors like ballpark, weather, or defense.

By converting this to the ERA scale, it puts xwOBA in numbers that are more familiar, and allows it to be compared directly to the pitcher's actual ERA. (If you're familiar with FIP, or Fielding Independent Pitching, the idea is similar, just that now Statcast quality of contact can be included.)

xERA is not necessarily predictive, but if a pitcher has an xERA that is significantly higher than his actual ERA, it should make you want to take a closer look into how he suppressed those runs.

Additional resources
• xERA leaderboard
• More about xERA

Source: MLB

Expected Fielding Independent Pitching (xFIP)

xFIP finds a pitcher's FIP, but it uses projected home-run rate instead of actual home runs allowed. The home run rate is determined by that season's league average HR/FB rate.

For example: In 2002, Randy Johnson had a 2.66 FIP and a 2.44 xFIP -- the difference being that he allowed a 12.9 percent HR/FB rate, when the league average stood at 10.7 percent.

The formula

Where "FIP constant" puts FIP on the same plane as league-average ERA: ((Fly balls / league average rate of HR per fly ball x 13) + (3 x (BB + HBP)) - (2 x K)) / IP + FIP constant.

Why it's useful

Like its cousin, FIP, xFIP can be used to portend future performance (as opposed to simply evaluating past results). However, xFIP and FIP differ in how they penalize pitchers for home run allowance. xFIP is predicated on the notion that pitchers have more control over how many fly balls they allow than how many of those fly balls leave the park. As a result, xFIP substitutes a pitcher's homer tally with an estimation of how many long balls that pitcher should have permitted given the number of fly balls he induced.

To determine the latter part of the equation, xFIP assumes a pitcher should have allowed a league average HR/FB rate, which was 15.3 percent in 2019. This assumption is drawn because HR/FB rate can fluctuate a lot from year to year, with pitchers often regressing back toward the league average rate.

Source: MLB

Expected Slugging Percentage (xSLG)

Expected Slugging Percentage (xSLG) is formulated using exit velocity, launch angle and, on certain types of batted balls, Sprint Speed.

In the same way that each batted ball is assigned an expected batting average, every batted ball is given a single, double, triple and home run probability based on the results of comparable batted balls since Statcast was implemented Major League wide in 2015. For the majority of batted balls, this is achieved using only exit velocity and launch angle. As of 2019, "topped" or "weakly hit" balls also incorporate a batter's seasonal Sprint Speed.

All hit types are valued in the same fashion for Expected Slugging Percentage as they are in the formula for standard slugging percentage, with doubles being worth twice as much, triples being worth three times as much and homers being worth four times as much as singles. The single, double, triple and home run probabilities for an individual batted ball are plugged into the formula for slugging percentage -- (1B + 2Bx2 + 3Bx3 + HRx4)/AB) -- to get a player's Expected Slugging Percentage on said batted ball.

Knowing the expected outcomes of each individual batted ball from a particular player over the course of a season allows for the formation of said player's seasonal Expected Slugging Percentage based on the quality of contact, instead of the actual outcomes. Likewise, this exercise can be done for pitchers to get their Expected Slugging Percentage against.

Why it's useful

Expected Slugging Percentage is more indicative of a player's skill than regular slugging percentage, as xSLG removes defense from the equation. Hitters, and likewise pitchers, are able to influence exit velocity and launch angle but have no control over what happens to a batted ball once it is put into play.

Source: MLB

Expected Weighted On-base Average (xwOBA)

Expected Weighted On-base Average (xwOBA) is formulated using exit velocity, launch angle and, on certain types of batted balls, Sprint Speed.

In the same way that each batted ball is assigned an expected batting average, every batted ball is given a single, double, triple and home run probability based on the results of comparable batted balls since Statcast was implemented Major League wide in 2015. For the majority of batted balls, this is achieved using only exit velocity and launch angle. As of 2019, "topped" or "weakly hit" balls also incorporate a batter's seasonal Sprint Speed.

All hit types are valued in the same fashion for xwOBA as they are in the formula for standard wOBA: (unintentional BB factor x unintentional BB + HBP factor x HBP + 1B factor x 1B + 2B factor x 2B + 3B factor x 3B + HR factor x HR)/(AB + unintentional BB + SF + HBP), where "factor" indicates the adjusted run expectancy of a batting event in the context of the season as a whole.

Knowing the expected outcomes of each individual batted ball from a particular player over the course of a season -- with a player's real-world data used for factors such as walks, strikeouts and times hit by a pitch -- allows for the formation of said player's xwOBA based on the quality of contact, instead of the actual outcomes. Likewise, this exercise can be done for pitchers to get their expected xwOBA against.

Why it's useful

xwOBA is more indicative of a player's skill than regular wOBA, as xwOBA removes defense from the equation. Hitters, and likewise pitchers, are able to influence exit velocity and launch angle but have no control over what happens to a batted ball once it is put into play.

For instance, Marcell Ozuna produced a .327 wOBA in 2018. But based on the quality of his contact, his xwOBA was .359.

Source: MLB

Extension (EXT)

A pitcher must begin his throwing motion while standing on the pitching rubber -- which is 60 feet, 6 inches away from home plate. This does not mean pitches are actually thrown from 60 feet, 6 inches away from the plate.

The point at which a pitcher releases the ball is actually a few feet closer to home plate than the pitching rubber itself. Extension quantifies exactly how much closer a pitcher's release point is to home plate. Taller pitchers with long wingspans tend to have the longest Extensions, because their frames allow them to hold on to the ball for a greater distance before releasing it.

Not surprisingly, a longer Extension can be a major advantage to pitchers, because they are essentially shortening the distance between themselves and opposing batters. A pitcher with a longer Extension can make a 93 mph fastball look like a 96 mph fastball. In this regard, Extension is a key component in the Statcast metric "Perceived Velocity."

In A Call

"His release point was X inches from the front of the rubber"

Source: MLB

Extra-base Hit (XBH)

An extra-base hit is defined as any hit that is not a single, meaning doubles, triples and home runs are all considered extra-base hits. They are a good stat to look at to evaluate an offensive player's power -- and in some cases, his speed.

An extra-base hit is typically a ball that is hit very hard, and it often goes to the outfield wall. (Obviously, in the case of a home run, it usually goes over the wall). Speedier hitters have a slight advantage in attaining extra-base hits because they can use their foot speed to reach second base faster.

Extra-base-hit totals can also be used to evaluate pitchers, although this is done less frequently. In that case, it is referred to as extra-base hits against.

In A Call

"extra bags," "long hit"

Source: MLB

F

Fair Ball

The foul lines and foul poles are used to demarcate fair territory and, thus, determine what constitutes a fair ball.

Any batted ball that first contacts a fielder while the ball is in fair territory is considered fair. If not touched by a fielder, any batted ball that first contacts the field in fair territory beyond first or third base -- with the foul lines and foul poles counting as fair territory -- is considered fair. Batted balls that first contact the field between home plate and first or third base are considered fair if they subsequently bounce over or directly contact either base, or otherwise pass either base while in fair territory. They are also considered fair if they settle in fair territory between home plate and first or third base, including instances in which they bounce off home plate.

Batted balls that directly strike either foul pole on the fly, or leave the park on a fly to the right of the left-field foul pole and to the left of the right-field foul pole are considered home runs.

Source: MLB

Field Dimensions

No Major League ballparks are exactly alike, but certain aspects of the field of play must be uniform across baseball.

The infield must be a square that is 90 feet on each side, and the outfield is the area between the two foul lines formed by extending two sides of said square (though the dirt portion of the field that runs well past the 90-foot basepaths in all Major League parks is also commonly referred to as the infield). The field must be constructed so that the bases are the same level as home plate.

The rulebook states that parks constructed by professional teams after June 1, 1958, must have a minimum distance of 325 feet between home plate and the nearest fence, stand or other obstruction on the right- and left-field foul lines, and 400 feet between home plate and the nearest fence, stand or other obstruction in center field. However, some clubs have been permitted to construct parks after that date with dimensions shorter than those specified.

The pitcher's plate must be a 24-inch by 6-inch slab of whitened rubber that is 10 inches above the level of home plate and 60 feet, 6 inches away from the back point of home plate. It is placed 18 inches behind the center of the mound -- which is erected within an 18-foot diameter circle -- and surrounded by a level area that is 5 feet by 34 inches. The slope of the pitcher's mound begins 6 inches in front of the pitcher's plate and must gradually decrease by 1 inch every foot for 6 feet in the direction of home plate.

Home plate is a 17-inch square of whitened rubber with two of the corners removed so that one edge is 17 inches long, two adjacent sides are 8 1/2 inches each and the remaining two sides are 12 inches each and set at an angle to make a point. The 17-inch side faces the pitcher's plate, and the two 12-inch edges coincide with the first- and third-base lines. The back tip of home plate must be 127 feet, 3 and 3/8 inches away from second base.

The other bases must be 15-inch squares that are between 3 and 5 inches thick, covered by white canvas or rubber and filled with soft material.

History of the rule

From the early 1900s through 1968, the pitcher's plate was permitted to be 15 inches above the level of home plate. That height was lowered to 10 inches starting with the 1969 season, in response to a 1968 campaign -- now known as the "Year of the Pitcher" -- in which the dominance of hurlers reached new heights.

The specification on minimum park dimensions was put into place due to the stadium controversy surrounding the Brooklyn Dodgers' move to Los Angeles in 1958. The Dodgers played at the Los Angeles Memorial Coliseum while Dodger Stadium was being built, but the Coliseum was not designed to hold baseball games. The Coliseum's left-field fence was roughly 250 feet away from home plate and the club had to erect a 40-foot-high screen to protect against short home runs. The specification is not strictly enforced, however, so long as teams do not build parks that egregiously violate the rule. For example, Petco Park opened in 2004 and is officially 396 feet in center field, and Oriole Park at Camden Yards opened in 1992 and is 318 feet down the right-field line.

 

Source: MLB

Fielder Right of Way

Fielders have a right to occupy any space needed to catch or field a batted ball and also must not be hindered while attempting to field a thrown ball.

If any member of the batting team (including the coaches) interferes with a fielder's right of way to field a batted ball, the batter shall be declared out. If any member of the batting team (including the coaches) interferes with a fielder's right of way to field a thrown ball, the runner on whom the play is being made shall be ruled out. In both cases, the ball will be declared dead and all runners must return to their last legally occupied base at the time of the interference. However, a runner is not obligated to vacate a base he is legally permitted to occupy to allow a defender the space to field a batted or thrown ball in the proximity of said base.

Interference can also be called on the offensive team if a batter hinders the catcher after a third strike when the ball is not caught, a batter intentionally deflects any foul ball, and a baserunner hinders a following play being made on another runner after having scored or been put out. When running the last half of the way to first base while the ball is being fielded in the vicinity of first, a baserunner must stay within the three-foot runner's lane to the right of the foul line unless they are avoiding a player fielding a batted ball. If the umpire determines that the baserunner has interfered with the player taking the throw at first base by running to the left of the foul line or to the right of the runner's lane, the baserunner can be called for interference.

Source: MLB

Fielding Independent Pitching (FIP)

FIP is similar to ERA, but it focuses solely on the events a pitcher has the most control over -- strikeouts, unintentional walks, hit-by-pitches and home runs. It entirely removes results on balls hit into the field of play.

For example: If a pitcher has surrendered a high average on balls in play, his FIP will likely be lower than his ERA. Balls in play are not part of the FIP equation because a pitcher is believed to have limited control over their outcome.

The formula

Where the "FIP constant" puts FIP onto the same scale as the entire league's ERA: ((HR x 13) + (3 x (BB + HBP)) - (2 x K)) / IP + FIP constant.

Source: MLB

Fielding Percentage (FPCT)

Fielding percentage answers the question: How often does a fielder or team make the play when tasked with fielding a batted ball, throwing a ball, or receiving a thrown ball for an out. The formula is simple: the total number of putouts and assists by a defender, divided by the total number of chances (putouts, assists and errors).

The league's lowest fielding percentages typically come from shortstops and third basemen, who must deal with a wide array of tricky ground balls and tough throws across the diamond. Conversely, catchers, first basemen and outfielders often have the highest fielding percentages because of the ease of the plays they have to make.

In A Call

"fielding average," "defensive percentage"

Source: MLB

First Baseman

The first baseman positions himself to the right of the first-base bag and toward the back of the infield dirt when no runner occupies first base or on the first-base bag after a batter reaches first base.

The first baseman is responsible not only for fielding ground balls hit in his vicinity but also for catching throws from other infielders to force a runner out at first base. The first baseman often has to "scoop" one-hop throws from an infielder or pick low throws out of the dirt.

Source: MLB

First-base Coach

The first-base coach stands in foul ground, just behind the first-base bag, and helps relay signals from the dugout to both batters and baserunners. First-base coaches often assist baserunners in picking the appropriate time to steal a base and alert baserunners as pitchers attempt to retire them via a pickoff throw. By rule, the first-base coach must stay within the designated coach's box on the first-base side of home plate prior to each pitch. The coach may leave said box to signal a player once a ball is in play, provided the coach does not interfere with the play.

Source: MLB

Fly-ball Rate (FB%)

Fly-ball rate represents the percentage of balls hit into the field of play that are characterized as fly balls. Each ball that is hit into the field of play is characterized as a line drive, a fly ball, a ground ball or a pop-up. (A fly ball is a fly to the outfield, while a pop-up is hit to the infield.)

Fly-ball rate can be used as a metric to evaluate both hitters and pitchers, although it's more frequently used to evaluate pitchers.

With pitchers, fly-ball rate can be very telling. For one thing, it tells us what type of pitcher we have. Pitchers with high fly-ball rates have a tendency to allow home runs (which result exclusively from fly balls and line drives). In this regard, pitchers generally strive to avoid high fly-ball rates. But some pitchers can thrive with a high fly-ball rate as long as they limit their home runs, because outs occur more frequently on fly balls than on ground balls.

In A Call

"fly-ball percentage"

Source: MLB

Flyout

A flyout occurs when a batter hits the ball in the air (not including balls designated as line drives) and an opposing defender catches it before it hits the ground or fence.

Certain pitchers -- generally those who pitch up in the zone frequently -- have a tendency to induce more flyouts than others. But that's a risky proposition, as fly balls can result in home runs, too.

In A Call

"fly-ball out," "can of corn," "pop-up," "pop out"

Source: MLB

Force Play

A force play occurs when a baserunner is no longer permitted to legally occupy a base and must attempt to advance to the next base. The defense can retire the runner by tagging the next base before he arrives, though not if the defensive team first forces out a trailing runner. In that instance, the force play is removed and the defense must tag the remaining runners to retire them.

First base tends to have the most force plays, as batters are eligible to be forced out at first any time they put the ball into fair territory and it is not caught in the air.

Source: MLB

Forearm Flexor Tendinitis

Repetitive motion can irritate, inflame or strain the flexor and pronator tendons in the forearm -- the ones that bend the wrist toward the palm -- where they attach to the medial epicondyle, which is the bony bump on the inside of the elbow that is actually the base of the humerus bone. Flexor tendinitis, also known as medial epicondylitis, can manifest as pain on the inside of the elbow, loss of range of motion or a popping or locking sensation.

Typical recovery time

A wide range of timetables exists for flexor tendon injuries. Depending on the severity, they can carry a recovery time of anywhere from 1-2 weeks to 1-2 months. If surgery is required, recovery can take upwards of six months.

Source: MLB

Forkball (FO)

One of the rarest pitches in baseball, the forkball is known for its severe downward break as it approaches the plate. Because of the torque involved with snapping off a forkball, it can be one of the more taxing pitches to throw.

Grip

When throwing a forkball, a pitcher jams the baseball between his index and middle fingers before releasing the pitch with a downward snap of the wrist. This causes the extreme downward movement on the baseball as it approaches the plate, similar to that of a 12-to-6 curveball.

The forkball is far more uncommon than its cousin, the splitter, which is gripped in similar fashion but closer to the tips of the fingers. Also, in contrast, a splitter does not require a wrist-snapping action.

Origin

Bullet Joe Bush, a right-hander who pitched from 1912-28, threw the pitch as an alternative to his curveball, which he could no longer throw because of the strain it put on his already fatigued arm. Other pitchers of that era threw similar variations of the forkball, but Bush is generally the player credited with having invented it.

In A Call

"fork"

Source: MLB

Foul Ball

The foul lines and foul poles are used to demarcate fair territory and, thus, determine what constitutes a foul ball.

Any batted ball that first contacts a fielder while the ball is in foul territory is considered foul. If not touched by a fielder in fair territory, any batted ball that first contacts the field in foul territory beyond first or third base -- with the foul lines and foul poles counting as fair territory -- is considered foul. Batted balls that first contact the field between home plate and first or third base are considered foul if they don't subsequently bounce over or directly contact either base, otherwise pass either base while in fair territory, or ultimately settle at some point in fair territory between home plate and either base.

Batted balls that leave the park on a fly to the left of the left-field foul pole or to the right of the right-field foul pole -- without striking the pole in either case -- are considered foul.

Source: MLB

Foul Tip

A foul tip is a batted ball that goes sharply and directly to the catcher's hand or glove and is legally caught. A foul tip is considered equivalent to a ball in which the batter swings and misses, in that the baserunners are able to advance at their own risk (without needing to tag up). Should the batter produce a foul tip after previously accruing two strikes, the foul tip is considered strike three and the batter is out.

The term "foul tip" is commonly used to describe any pitch that is slightly struck into foul territory, but the ball must be caught by the catcher in order for it to be considered a foul tip by rule. If the ball is not caught by the catcher, it is considered a regular foul ball and the baserunners are not able to advance.

Source: MLB

Four-Seam Fastball (FA)

A four-seam fastball is almost always the fastest and straightest pitch a pitcher throws. It is also generally the most frequently utilized.

The four-seam fastball is typically one of the easiest pitches for a pitcher to place, because of the lack of movement on the pitch. It is often used to overpower hitters, with the goal being for the pitch to get to the strike zone faster than the hitter can handle, thus creating a swing and miss or weak contact because of a late swing. The pitch derives its name because upon being released, four seams come into view on the ball with each rotation.

Grip

In order to throw a four-seam fastball, a pitcher grips the ball with his two fingers across the open space between seams and the edges of his fingers slightly over the seam. This is the way fielders are typically instructed to throw the ball, because it produces the straightest plane.

In A Call

"four-seamer," "heat," "heater," "high cheese," "cheese," "rising fastball"

Source: MLB

Free Agency

Players become free agents upon reaching six years of Major League service time or when they are released from their organization prior to reaching six years of service time. A free agent is eligible to sign with any club for any terms to which the two parties can agree. If a player with fewer than six years of service time signs with a club, he remains under the control of that club until reaching the requisite service time to reach free agency -- even if the contract he signed does not cover the remaining years until that point.

Examples

Jason Heyward made his Major League debut on Opening Day in 2010 and never returned to the Minor Leagues. He reached six years of Major League service time at the completion of the 2015 season, at which point he became eligible for free agency. Heyward went on to sign an eight-year contract with the Cubs.

Tony Sipp was released by the Padres in May 2014 when he had between four and five years of Major League service time. The left-hander subsequently signed a guaranteed Major League contract with the Astros that ran through the end of the '14 campaign. Because he finished the season with less than six years of Major League service time, Sipp was eligible for salary arbitration as opposed to free agency. Sipp qualified as a free agent following the 2015 season and re-signed with the Astros on a three-year deal.

Source: MLB

G

Game Score

Game Score measures a pitcher's performance in any given game started. Introduced by Bill James in the 1980s and updated by fellow sabermetrician Tom Tango in 2014, Game Score is presented as a figure between 0-100 -- except for extreme outliers -- and usually falls between 40-70.

A Game Score of 50 is considered "average," while a Game Score of 40 is deemed to be "replacement level." Game Scores in the 80s and 90s are widely regarded as impressive, and scores of at least 100 are exceptionally rare. Using Tango's formula, which is the version displayed on MLB.com, only nine of the 4,858 games started in 2015 resulted in Game Scores of 100-plus.

A Game Score is derived by factoring the quality (based on runs, hits, HR, walks, strikeouts) and quantity (innings) of a starting pitcher's performance

Although James' and Tango's Game Score formulas lie in great parallel, they also diverge in ways that cause Tango's version to be slightly more linked to a pitcher's talent level. In the updated version, the following changes were made:

• A baseline score was moved from 50 to 40. This change prevents very short outings from being calculated as near average. (Ex. With a 50-score baseline, a starting pitcher could strike out the first batter of the game and be removed to record a Game Score of 52 -- above average. In reality, though, the starting pitcher being lifted after one out puts the team in a highly unfavorable position.

• A penalty for home runs allowed was implemented. Home runs allowed was not part of the initial formula -- created using the official line score in a box score -- despite their significant impact on a team's chances of victory.

• The penalty for a walk allowed was doubled from -1 to -2, to be in line with the penalty for a non-homer hit (single, double, triple). Although a non-homer hit is more impactful than a walk, both events are viewed equally when determining a player's talent level.

The formula

Game Score formula (created by Bill James)

• Start with 50 points
• Add 1 point for each out recorded (or 3 points per inning)
• Add 2 points for each inning completed after the fourth
• Add 1 additional point for every strikeout
• Remove 2 points for each hit allowed
• Remove 4 points for each earned run allowed
• Remove 2 points for each unearned run allowed
• Remove 1 point for each walk allowed

Game Score formula (updated by Tom Tango)

• Start with 40 points
• Add 2 points for each out recorded (or 6 points per inning)
• Add 1 additional point for every strikeout
• Remove 2 points for each walk allowed
• Remove 2 points for each hit allowed
• Remove 3 points for each run allowed (earned or unearned)
• Remove 6 additional points for each home run allowed

Using the James formula, Kerry Wood posted a Game Score of 105 -- the highest ever in a nine-inning game -- on May 6, 1998, when he allowed only one hit with no walks and 20 strikeouts in a complete-game shutout vs. the Astros. Using the Tango formula, Wood's Game Score was 112.

With James' formula, Wood started with a baseline score of 50 and received 37 points for his nine innings of work (1 point for each out and 2 points for each inning completed after the fourth) and 20 points for his 20 K's while losing two points for his lone hit allowed. With Tango's, Wood started with a baseline score of 40 and received 54 points for his nine innings of work (2 points for each out) and 20 points for his 20 K's while losing two points for his lone hit allowed.

Conversely, Max Scherzer's Game Score in his 20-strikeout performance vs. the Tigers on May 11, 2016, was higher using the James formula (87) than the Tango formula (84). Scherzer allowed two runs on six hits (two homers) with no walks with 20 K's over nine innings. With James' formula, Scherzer wasn't penalized for allowing two home runs, but his Game Score was reduced by six points per homer using Tango's formula.

Why it's useful

Game Score allows for a quick assessment of a particular pitcher's performance, simply by looking at one, easy-to-understand number. Furthermore, Game Score correlates strongly with winning percentage, so that a pitcher with an average Game Score of 60 can be expected to win approximately 60 percent of the time.

Source: MLB

Games Finished (GF)

A pitcher is credited with a game finished if he is the last pitcher to pitch for his team in a given game, provided he was not the starting pitcher. Starters are not credited for a game finished when they pitch a complete game.

Typically, a team's closer will be the team leader in this category, because games finished is generally a good indicator of when and how a relief pitcher is used. However, closers aren't the only pitchers to record high totals of games finished. In every game in which a team uses a relief pitcher -- no matter the score or the result -- there will be someone recording a game finished. Saves, on the other hand, require a unique set of circumstances and a specific accomplishment.

In A Call

"finishes," "he finishes it out"

Source: MLB

Games Played (G)

A player is credited with having played a game if he appears in it at any point -- be it as a starter or a replacement. It's important to note that the player doesn't necessarily need an at-bat. He can also enter for defense or as a pinch-runner.

Typically, if a player records 162 games played, it means that he appeared in every game that season. But there have been instances in the past where players have exceeded that number -- either because they were traded during the season or because they played in a tiebreaker game at the end of the season.

In A Call

"games," "appearances"

Source: MLB

Games Started (GS)

A pitcher is credited with a game started if he is the first pitcher to throw a pitch for his team in a given game. A starter who pitches a full season in a five-man rotation will generally tally at most 34 games started. There is no minimum innings plateau for a pitcher to earn a game started, but a starter must pitch at least five innings to be eligible for a win.

Beginning in 2018, teams started experimenting with the idea of using an "opener." Much like a closer, the opener is responsible only for an inning (sometimes two). The opener generally gives way to a reliever in the second or third inning. The prevailing wisdom behind an opener is that it's better for a quality reliever to face the top of the order early in a game than a team's fourth-best or fifth-best starting option. It can also be beneficial to have a right-handed opener face an all-right-handed top of the order or a left-handed opener face multiple imposing lefties. Openers are credited with games started and generally have the opportunity to make more starts than a traditional starting pitcher would over the course of a full season.

In A Call

"starts"

Source: MLB

General Manager

In most organizations, the general manager has final say in terms of roster decisions (e.g. trades, free-agent signings) and coaching/front office personnel (e.g. hiring, firing, promotions, reassignments). In organizations that employ a president of baseball operations, the general manager is considered second in command. Not every club employs a president of baseball operations, though some examples include the 2016 Cubs (Theo Epstein), '16 Dodgers (Andrew Friedman) and '16 Indians (Chris Antonetti).

General managers have a number of assistants, as well as scouts and statistical analysts, working underneath them. Additionally, general managers also act as a face of a franchise in terms of speaking to the media and making public appearances.

Source: MLB

Grand Slam (GSH)

A grand slam occurs when a batter hits a home run with men on first base, second base and third base. Four runs score on a grand slam -- the most possible on one play -- and a batter is awarded four RBIs.

Understandably, a grand slam usually has an immense impact on the result of the game, because four runs score on the play.

Grand slams are rare. They are also entirely a result of the circumstances, meaning some of the game's greatest sluggers haven't hit many grand slams simply because the situation (three men on base) doesn't present itself often.

Origin

The term originated in the card game Bridge, referring to a player winning every trick. It carried over into baseball because it refers to a team scoring as many runs as possible in one at-bat.

In A Call

"slam," "salami," "grand salami," "grand-slam home run"

Source: MLB

Ground Into Double Play (GIDP)

A GIDP occurs when a player hits a ground ball that results in multiple outs on the bases. The most common double plays are ground balls where a forceout is made on the player running from first to second base, then another forceout is made on the batter running to first base.

A GIDP typically occurs on a ground ball that is hit hard and directly at a fielder, although softly hit balls can also result in double plays depending on the speed of the batter running to first base. The MLB leaders in GIDP are typically slower players who hit a high number of ground balls -- often well-struck ground balls.

GIDP can be used to evaluate pitchers as well. For most pitchers, the goal is to keep the ball low in the strike zone, and GIDPs are typically a result of success in that regard. It is often said that double plays are "a pitcher's best friend."

In A Call

"twin killing," "turn two"

Source: MLB

Ground Rules

The Commissioner's Office issues a list of universal ground rules that are to be used in every Major League ballpark each season. Individual parks then are able to institute their own special ground rules, covering instances in which the intricacies of said parks might influence the game. For example, Tropicana Field has a number of special ground rules regarding occurrences of a batted ball striking a catwalk, light or another suspended object.

The home team is the sole judge as to whether a game shall not begin due to unsuitable weather or playing-field conditions, except for the second game of a doubleheader. In the latter instance, the umpire-in-chief of the first game of the doubleheader shall make that call.

For ballparks with retractable roofs, the decision to begin the game with the roof open or closed rests with the home team during the regular season. The roof can be closed only for weather reasons if the game begins with the roof open. If the game begins with the roof closed, it can be reopened once if the home team determines the climatic environment has reached a level where fan comfort and enjoyment will be best served by opening the roof. The roof may be moved only once during a game, unless inclement weather indicates otherwise. During the postseason, the Commissioner or another designated official shall make all decisions regarding roof movement, in consultation with the home club and the umpire crew chief.

Source: MLB

Ground-ball Rate (GB%)

Ground-ball rate represents the percentage of balls hit into the field of play that are characterized as ground balls. Each ball that is hit into the field of play is characterized as a line drive, a fly ball, a ground ball or a pop-up. Ground-ball rate can be used as a metric to evaluate both hitters and pitchers.

Pitchers with high ground-ball rates have a tendency to allow fewer home runs (which result from fly balls and line drives). Likewise, hitters with higher ground-ball rates tend to hit fewer home runs.

In A Call

"ground-ball percentage"

Source: MLB

Groundout

A groundout occurs when a batter hits a ball on the ground to a fielder, who records an out by throwing to or stepping on first base. It can also occur when the batter reaches first base -- and the defense instead opts to record an out elsewhere via a "fielder's choice."

Groundouts typically occur on pitches that are lower in the strike zone. They also occur most frequently on pitches with sharp downward movement -- such as sinkers or sliders -- because the batter doesn't have much time to adjust his swing for the baseball's sudden drop.

Many pitchers aim to induce ground balls -- as opposed to fly balls -- because ground balls rarely result in extra-base hits.

In A Call

"ground-ball out," "chopper," "bouncer"

Source: MLB

Groundout-to-Airout Ratio (GO/AO)

Groundout-to-airout ratio is obtained by dividing the total number of ground balls converted into outs (not including bunts) by the total number of balls in the air (fly balls and line drives) converted into outs.

For pitchers, GO/AO can often be an indicator of success, because a pitcher generally aims to induce more ground balls than balls in the air (seeing as how these batted balls can turn into the most harmful result of all, a home run). But at the same time, certain pitchers can thrive while still allowing a high percentage of balls in the air, as long as they're inducing weak contact and/or striking out hitters.

For hitters, this number is used much less frequently as an evaluation tool, although speedier hitters typically strive for a higher ratio of ground balls to fly balls. That's because over the course of a season, some would-be groundouts become infield hits for batters who are fast enough to beat the throw.

Source: MLB

Guaranteed Contract

Players who obtain Major League contracts -- either via free agency or extensions -- are guaranteed the full amount of money promised by those contracts. Conversely, players signed to Minor League contracts must earn a spot on the roster in Spring Training or via an in-season promotion in order to have their contracts guaranteed. Arbitration contracts are not guaranteed either, as a club can release a player on or before the 16th day of Spring Training and be responsible for only 30 days worth of pay. Players cut between the 17th and the final day of Spring Training must be compensated for 45 days worth of pay (at the prorated version of their arbitration salary). But if a player that agreed to an arbitration salary breaks camp with the club, his contract is fully guaranteed.

Example

Right-hander Josh Johnson signed a one-year, $8 million contract with the Padres prior to the 2014 season. Despite the fact that he did not throw a single inning for the Padres, he earned the entirety of that $8 million because he had signed a Major League contract.

Source: MLB

H

Hamstring Strain

At the back of each thigh are three hamstring muscles -- the semitendinosus, semimembranosus and biceps femoris, from the inside to the outside. At the top, or proximal end, the three muscles come together, form the hamstring tendon and attach at the base of the pelvis on the ischial tuberosity, or the sitting bone. They run down the back of the thigh, cross the knee joint and attach distally to the tibia and fibula bones in the lower leg. The hamstring muscle group is responsible for the flexing of the lower leg at the knee.

Injuries occur when there is a muscular imbalance, when the hamstrings are not adequately warmed up or are fatigued, or when a sudden burst of speed is required.

Most hamstring strains in baseball occur between the middle of the muscle and the proximal attachment at the pelvis. As with all muscle strains, they are rated by grade. Grade 1 is a mild strain or pull, Grade 2 is a partial tear and Grade 3 is a complete tear in which the hamstring tendon lifts completely away from the bone.

Typical recovery time

Lower-grade injuries can be treated with simple rest, with dry needling to relax angry muscle fibers and reset nerve fibers, or with biologic solutions such as platelet-rich plasma (PRP) or stem-cell injections. Depending on severity of the injury, players may return to play in as little as a few days or as long as a few months. Full tears may need to be repaired surgically and sutured back to the bone, with a return to play in 3-4 months.

 

Source: MLB

Hard-hit Rate

Statcast defines a 'hard-hit ball' as one hit with an exit velocity of 95 mph or higher, and a player's "hard-hit rate" is simply showing the percentage of batted balls that were hit at 95 mph or more.

Why 95 mph? Because, as the image below shows, that's when exit velocity begins to "matter." Another way of saying that is that balls hit at 40 mph or 70 mph will affect your average exit velocity differently, but in terms of outcomes, they're just two varieties of weakly hit balls. For true production, you need to get to 95 mph.

 

You can see the value when you look at the 2018 MLB outcomes for hard-hit balls (95 mph+) and weakly-hit balls (below 95 mph).

Hard-hit balls
.524 BA, 1.047 SLG, .653 wOBA

Weakly hit balls
.219 BA, .259 SLG, .206 wOBA

Source: MLB

Hit (H)

A hit occurs when a batter strikes the baseball into fair territory and reaches base without doing so via an error or a fielder's choice. There are four types of hits in baseball: singles, doubles, triples and home runs. All four are counted equally when deciphering batting average. If a player is thrown out attempting to take an extra base (e.g., turning a single into a double), that still counts as a hit.

Hits come in all varieties. Some can be hard-hit balls or long home runs. Others can be slow bouncers in the infield -- or even bunts -- where the batter reaches first base before the throw. (These are called "infield hits.") Hits are also credited to the batter when the ball takes an awkward bounce that a defender cannot field (provided the scorer rules that the batter didn't reach base with the help of an error).

The league leader in hits is often a batter with speed who:

Hits high in the batting order -- meaning he gets a high number of plate appearances
Doesn't walk much
Makes a lot of hard contact
Hits are a pivotal part of many statistics, such as batting average, batting average against, WHIP and H/9.

In A Call

"base hit," "knock," "base knock"

Source: MLB

Hit Distance (DST)

Hit Distance represents the distance away from home plate that a batted ball lands -- whether by hitting the ground, the seats, the wall or a fielder's glove.

Average Hit Distance (aDST) is calculated by: the sum of all Hit Distances, divided by all Batted Ball Events.

Statcast can record Hit Distances at the moment a ball touches the ground or where a ball ultimately ends up. A batted ball's farthest distance relative to home plate arguably tells the most accurate story of a Batted Ball Event.

In A Call

"carry," "length"

Source: MLB

Hit-by-pitch (HBP)

A hit-by-pitch occurs when a batter is struck by a pitched ball without swinging at it. He is awarded first base as a result. Strikes supersede hit-by-pitches, meaning if the umpire rules that the pitch was in the strike zone or that the batter swung, the HBP is nullified.

A batter is awarded a hit-by-pitch, even if the ball only touches a portion of his uniform or protection (helmet, shin guard, etc.).

Most hit-by-pitches are unintentional. They often stem from pitchers trying to throw the ball inside but missing by a few inches. Pitchers will often throw inside to make the hitter wary, so they do not crowd the plate. However, a pitcher may sometimes throw at a hitter intentionally as a form of retaliation. If the home-plate umpire suspects this is the case, he has the right to eject the pitcher (and the manager of the pitching team) from the game.

A hit-by-pitch does not count as a hit, but it does count as a time on base for on-base percentage purposes. Certain hitters -- specifically those who stand very close to the plate -- have a knack for earning HBPs, which can obviously be helpful because the goal of any hitter is to reach base. But hit-by-pitches can also result in injury because most pitches are thrown 80 mph or faster. Per the rules, a batter must make an attempt to avoid being hit by a pitch in order to receive first base.

Pitchers with high HBP totals typically struggle with their control and will also walk a higher-than-normal number of hitters.

In A Call

"plunked," "drilled," "hit batter," "hit batsman"

Source: MLB

Hits Per Nine Innings (H/9)

H/9 represents the average number of hits a pitcher allows per nine innings pitched. It is determined by dividing a pitcher's hits allowed by his innings pitched and multiplying that by nine. It's a very useful tool for evaluating pitchers, whose goal is to prevent runs, which are usually scored by hits.

Though it's closely correlated with opponents' batting average, hits per nine is based solely on the number of outs a pitcher records, rather than the number of at-bats by his opponents. This is important because H/9 takes into account the second out on double plays, sacrifices and other outs that occur without an official at-bat being recorded -- such as outfield assists. Walks, hit by pitches and other means of reaching base do not play a factor in H/9.

In A Call

"hits per nine"

Source: MLB

Hitting Coach

Hitting coaches instruct players on matters related to hitting, such as batting mechanics, plate discipline and preparation.

Hitting coaches in today's game leverage video footage to prepare hitters for opposing pitchers and to help identify flaws or bad habits in hitters' at-the-plate approach.

Every Major League club has a hitting coach, and some also employ an assistant hitting coach.

Source: MLB

Hold (HLD)

A hold occurs when a relief pitcher enters the game in a save situation and maintains his team's lead for the next relief pitcher, while recording at least one out. One of two conditions must be met for a pitcher to record a hold: 1) He enters with a lead of three runs or less and maintains that lead while recording at least one out. 2) He enters the game with the tying run on-deck, at the plate or on the bases, and records an out.

As a statistic, holds are designed to credit late-relief pitchers who are not closers. For those pitchers, their primary job is to not relinquish the lead, while getting the ball to the next reliever in line. Every save opportunity in which a pitcher records at least one out will result in either a save, a blown save or a hold.

A pitcher cannot receive a win or a save in a game in which he records a hold. However, more than one relief pitcher can record a hold in a single game. It is also possible for a pitcher to receive a hold and a loss in the same game should he exit with the lead, only to see the runners he left on base score the tying and go-ahead runs.

Origin

The hold was invented in the 1980s by statisticians John Dewan and Mike O'Donnell as a means to quantify the effectiveness of relievers who aren't closers. The statistic was meant to value setup men -- who traditionally pitch the eighth inning before the closer pitches the ninth.

Source: MLB

Home Run (HR)

A home run occurs when a batter hits a fair ball and scores on the play without being put out or without the benefit of an error.

In almost every instance of a home run, a batter hits the ball in the air over the outfield fence in fair territory. In that situation, the batter is awarded all four bases, and any runners on base score as well. The batter can circle the bases at his leisure, as there is no threat of him being thrown out. (This also occurs when the ball hits the foul pole in left or right field, or when the ball hits an opposing defender on the fly and bounces directly over the wall in fair ground.)

There are also instances of "inside-the-park home runs." These occur when the batter hits the ball in play (not over the wall) and touches all four bases without being thrown out. These are extremely rare and typically only occur with a very fast runner at the plate and some sort of misplay by an outfielder that doesn't qualify as an error.

Home runs can be a great stat for evaluating a hitter's power. They're also good for measuring the success of pitchers, who strive to limit home runs. But home run totals can be affected by the ballpark in which a game is being played. Some ballparks are smaller, have higher walls or have different wind currents. This means home runs in certain ballparks might have stayed in the yard in others.

Origin

The term "home run" comes from the basic act of a batter circling all the bases successfully. In the early days of the home run, running was typically a necessity as players weren't very powerful and outfields were much bigger, leading to a greater number of inside-the-park home runs. Now, however, most home runs feature players trotting around the bases after hitting the ball over the fence.

In A Call

"homer," "long ball," "dinger," "tater," "jack," "shot," "four-bagger," "blast," "big fly," "going yard," "going deep," "clout," "round tripper," "gopher ball" (used to describe the home run pitch thrown by the pitcher)

Source: MLB

Home Run To Fly Ball Rate (HR/FB)

Home-run-to-fly-ball (HR/FB) rate is the rate at which home runs are hit against a pitcher for every fly ball he allows. It's as simple as the name makes it sound. The league average HR/FB rate is usually slightly below 10 percent.

For example, if a pitcher faces 25 batters -- 10 of whom hit fly balls -- and he surrenders one home run, his HR/FB rate is 10 percent.

The formula

Home runs / total fly balls, including home runs.

Why it's useful

Research shows that the HR/FB rate of individual pitchers can vary greatly from year to year. That means pitchers with high HR/FB rate have generally -- but not always -- experienced some bad luck.

Source: MLB

Home Runs Per Nine Innings (HR/9)

HR/9 represents the average number of home runs allowed by a pitcher on a nine-inning scale. The statistic is determined by dividing a pitcher's home runs allowed by his total innings pitched and multiplying the result by nine.

HR/9 is a statistic that -- relatively speaking -- is in the control of the pitcher, because defensive positioning plays no factor. Certain pitchers can have success with a high HR/9 rate, as long as they manage to limit their baserunners otherwise -- leading to fewer multi-run home runs. Pitchers with high fly-ball rates are more likely than ground-ball pitchers to have high HR/9 rates. However, some pitchers have mastered the art of allowing fly balls but not many home runs.

In A Call

"homers per nine"

Source: MLB

Home To First

Home to First readings measure the time elapsed from the point of bat-on-ball contact to the moment the batter reaches first base. Statcast has the ability to filter Home to First readings, which can be useful when attempting to discern a hitter's ability to "beat out" a ground ball hit to an infielder. In some scouting circles, a hitter's Home to First time on infield ground balls is sometimes referred to as "dig speed."

Players with the fastest times generally tally the most infield hits. Said players also tend to force defenses into committing errors, as fielders must rush to retire the speedy runner at first base.

As left-handed hitters stand closer to first than right-handed hitters, they are generally represented well on Home to First leaderboards.

In A Call

"He got to first in X seconds," "home to first in X seconds," "he got down the line in X seconds"

Source: MLB

I

Incentive Clause

Incentives in contracts allow players to earn additional money by achieving certain predetermined benchmarks. Major League Baseball's Basic Agreement prohibits incentives from being awarded based on statistical achievement. Thus, playing time is the near-universal means by which players receive incentives. Pitchers with incentive-laden contracts typically trigger the incentives based on number of innings pitched, number of games started, number of relief appearances, number of games finished, etc. Hitters will most commonly trigger incentives based on plate appearances. Some contracts also contain roster bonuses, which reward a player simply for staying on the active roster for a certain number of days.

In the 2011 wave of collective bargaining agreement negotiations, milestone bonuses were prohibited by the league, meaning that players can no longer receive contractual bonuses for reaching plateaus such as their 3,000th hit, 500th home run, 200th win, etc.

Example

In the 2015-16 offseason, the Astros signed Doug Fister to a one-year contract with a $7 million guarantee. His contract contained up to $5 million worth of incentives, allowing him to earn a maximum of $12 million for the 2016 season.

Source: MLB

Infield Fly

An infield fly is any fair fly ball (not including a line drive or a bunt) which can be caught by an infielder with ordinary effort when first and second or first, second and third base are occupied, before two men are out. The rule is in place to protect against a team allowing a shallow fly ball to drop in with the intention of causing a force play at second and third or second, third and home. Otherwise, the team would be able to force out baserunners who had stayed put on a routine fly ball.

In these situations, the umpire will declare "infield fly" for the benefit of the baserunners as soon as it is apparent that the fly ball qualifies as an infield fly. The batter is out even if the ball is not caught, and the baserunners can advance at their own risk. If the ball is caught, the baserunners can attempt to advance as they would on a typical ball caught in the air.

Source: MLB

Inherited Runs Allowed Percentage (IR-A%)

IR-A% denotes the percentage of inherited runners who come around to score against a relief pitcher. It is determined by dividing the inherited runs scored against a pitcher by the total number of runners he has inherited. This statistic essentially asks the question: How often does a relief pitcher allow a runner (or multiple runners) to score when he enters the game with a runner (or multiple runners) on base?

Any baserunners allowed by a relief pitcher do not factor into his eventual IR-A percentage. Therefore, IR-A percentage has no bearing on a reliever's ERA.

In A Call

"inherited-run rate," "inherited-run-scored rate," "strand rate" (opposite)

Source: MLB

Innings Per Start (I/GS)

Innings per start signifies the average number of innings a pitcher throws per game started and is determined by dividing his innings pitched by his starts.

In A Call

"innings per game started," "average start length"

Source: MLB

Innings Pitched (IP)

Innings pitched measures the number of innings a pitcher remains in a game. Because there are three outs in an inning, each out recorded represents one-third of an inning pitched.

Just because a pitcher appears in a game, doesn't mean he will record an inning pitched or even a third of an inning pitched. In order for a pitcher's IP total to increase, he must be pitching while an out is recorded. This includes pickoffs and caught stealings, while double plays are worth two-thirds of an inning pitched.) Pitchers are not credited for a third of an inning pitched if a batter reaches on an error because an out was never recorded.

In A Call

"innings," "innings of work," "frames"

Source: MLB

Innings Played (INN)

Innings played is a defensive statistic determined by counting the number of outs during which a player is in the field and dividing by three.

Innings played is often used by voters to delineate players who have played enough at a given position to consider merit for defensive awards, specifically Gold Gloves. However, it is not used as the qualifying metric for the fielding percentage leaderboards. Instead, the total games played at a position are used for determining whether a defensive player qualifies as a fielding percentage leader.

Still, innings played defensively can be a valuable sorting tool for defensive statistical searches.

In A Call

"innings," "defensive innings played"

Source: MLB

Intentional Walk (IBB)

An intentional walk occurs when the defending team elects to walk a batter on purpose, putting him on first base instead of letting him try to hit. Intentional walks -- which count as a walk for the hitter and a walk allowed by the pitcher -- are an important strategy in the context of a game. They can be used to put a runner on first base, setting up a potential double play.

Intentional walks occur most frequently with an excellent hitter at the plate and a significantly worse hitter -- or a more favorable matchup for the pitcher -- on deck. Generally, intentional walks occur with no one on first base, but they can also occur -- very, very rarely -- with first base occupied.

Beginning in the 2017 season, teams no longer need to throw four balls in order to intentionally walk a batter. Rather, the manager can signal an intentional walk from the dugout at any point during a plate appearance, putting the batter on first base automatically.

History of the rule

Prior to the 2017 season, teams were not able to intentionally walk a batter without throwing four balls -- though only the fourth ball needed to be intentional in order for the walk to be scored as such.

For intentional walks, a catcher would typically stand upright -- by rule keeping both feet inside the catcher's box until the ball left the pitcher's hand -- so he could more easily receive a pitch far outside the strike zone. Of course, hitters were not prohibited from swinging at an intentional ball attempt and would occasionally do so if the pitch was thrown closer to the plate than the pitcher intended.

In A Call

"free pass," "putting him on"

Source: MLB

Intercostal Strain

The 11 intercostal muscles on each side of the rib cage connect one rib to another, working to spread the ribs apart and bring them back together again as the chest expands and contracts during breathing. The intercostals are also part of the core muscle group that is integral to many fundamental baseball movements. They are most often injured during a sudden contraction when they are in a stretched position, such as during a throw or swing. Because the lungs are located inside the rib cage, pain from a strained intercostal can be so severe that it feels like a broken rib.

Like all muscle strains, the intercostal strain is broken down into three grades. Grade 1 is a mild strain, Grade 2 is a moderate strain and Grade 3 is a severe strain in which the muscle ruptures.

Typical recovery time

Recovery time is dependent on the severity of the strain, with Grade 1 strains typically requiring 2-3 weeks and Grade 2 strains taking twice as long. Grade 3 strains often require surgery, however, with a 3-4 month recovery window.

In 2014, Dexter Fowler missed eight weeks with an intercostal strain. Carlos Gomez missed three weeks in 2017. David Wright missed one month of Spring Training in 2012 and then missed time in the spring of 2013 at the World Baseball Classic with the same injury.

Source: MLB

International Amateur Free Agency & Bonus Pool Money

As per the 2017-21 Collective Bargaining Agreement, clubs are each subject to a spending cap for amateur international free agents. Each club will have at least a $4.75 million bonus pool to spend, with those that have a pick in Competitive Balance Round A receiving $5.25 million and those with a pick in Competitive Balance Round B receiving $5.75 million.

Clubs will be able to acquire up to 75 percent of their initial international bonus pool money in the 2017-18 and 2018-19 signing periods and up to 60 percent of their initial pools in subsequent signing periods. This means that a club with an initial pool of $5.75 million can increase its pool total via trade to approximately $10.1 million during the 2017-18 and 2018-19 signing periods. The 2017-21 CBA also allows international funds to be traded more freely, as teams must now simply trade international money in increments of $250,000, unless they have less than $250,000 remaining in their pool. Under the 2012-16 CBA, teams were assigned four tradeable "slots" with different values designated for each slot. The money was able to be traded only in those increments.

Beginning in the 2017-18 offseason, any team that is over the luxury tax threshold and signs a Major League free agent that has rejected a qualifying offer will lose $1 million from their international signing pool in the following signing period. A team that is not over the luxury tax would only forfeit $500,000 of its signing pool in the subsequent period.

Each year's international signing period begins July 2 and continues through June 15 of the following year. Under the CBA, international amateurs are defined as follows:

• Player resides outside of the United States, Canada or Puerto Rico and has not been enrolled in high school in any of those locations within the past calendar year.
• Player is at least 16 years of age or will turn 16 years of age prior to Sept. 1 of the current signing period.

Any player meeting that criteria becomes eligible to sign a Minor League contract with a Major League organization for a signing bonus that fits within said team's allotted pool. Players that sign for a total bonus of $10,000 or less do not count against a team's allotted bonus pool.

Foreign professionals -- defined as players who are at least 25 years of age and have played as a professional in a foreign league recognized by Major League Baseball for a minimum of six seasons -- maintain exemption from the international bonus pool.

Clubs that accrued penalties for exceeding their international bonus pool money under the stipulations of the 2012-16 Collective Bargaining Agreement will not have those penalties wiped out by the 2017-21 CBA.

History of the rules

Under the terms of the 2012-16 Collective Bargaining Agreement, international pool money was scaled based on the previous season's standings. Clubs were also able to exceed their international bonus pool, but they had to pay a luxury tax for doing so.

In addition, clubs that exceeded their pool by five to 10 percent were banned from signing a player for more than a $500,000 bonus the following signing period. For clubs that exceeded their pool by 10 to 15 percent, the maximum bonus they were able to offer dropped to $300,000 during the next signing period. Finally, clubs that exceeded their pool by more than 15 percent were not allowed to sign a player for more than $300,000 during the next two signing periods.

International bonus money was also tradeable under the 2012-16 Collective Bargaining Agreement, but each club's bonus pool was divided into four "slots." For instance, a club with a $3 million pool might have had a $1.5 million slot, an $800,000 slot, a $400,000 slot and a $300,000 slot. The money was able to be traded only in those increments. Moreover, clubs were able to acquire no more than 50 percent of their original pool size.

Also of note: Previously, foreign-born players were granted exemption from the amateur-bonus-pool rules if they were at least 23 years of age with at least five seasons in a professional league recognized by Major League Baseball.

Source: MLB

International Free Agency -- Asia (Professional)

Players that accrue nine years of service time in Japan's Nippon Professional Baseball or the Korea Baseball Organization are considered free agents. Such players are eligible to pursue opportunities in any league, including Major League Baseball, without being subjected to the Korean or Japanese posting systems.

Clubs are able to offer any dollar amount they wish to such players, as they are not subject to international amateur free agency spending restrictions.

Example

The Yankees signed Japanese outfielder Hideki Matsui to a three-year, $21 million contract in December 2002, without having to go through the posting process. Before becoming a free agent, Matsui had played in Japan with the Yomiuri Giants from 1993-2002.

Source: MLB

International Free Agency -- Cuba (Professional)

While most international free agents from Latin America sign as amateurs during their teenage years, Cuba has its own top professional league: the Cuban National Series (Serie Nacional). Players with enough experience as a professional in Cuba are exempt from MLB's international bonus pools.

Any player 25 years of age or older with at least six seasons in Serie Nacional is considered a professional rather than an amateur. These players may sign a Major League or Minor League contract with any team for any amount, just as a domestic free agent would, without penalty for the signing team.

Example

Cuban-born first baseman Jose Abreu signed a Major League contract with the White Sox in October 2013. Major League Baseball had different international free-agency specifications at that point, offering unrestricted free agency to players aged 23 and older who had at least five years of professional experience. Given he was 26 years old at the time of the signing and had already played parts of 10 professional seasons in Cuba, Abreu would have qualified for unrestricted free agency under the current rules as well.

Source: MLB

Isolated Power (ISO)

ISO measures the raw power of a hitter by taking only extra-base hits -- and the type of extra-base hit -- into account.

For example, a player who goes 1-for-5 with a double has an ISO of .200. A player who goes 2-for-5 with a single and a double has a higher batting average than the first player, but the same ISO of .200.

The formula

(1x2B + 2x3B + 3xHR) / At-bats OR Slugging percentage - Batting average

Why it's useful

By focusing strictly on extra-base hits, ISO can help evaluate the raw power a player has.

Source: MLB

J

JAWS

JAWS (Jaffe Wins Above Replacement Score) is a system created by Jay Jaffe that evaluates a player's worthiness for enshrinement in the National Baseball Hall of Fame by comparing him to the Hall of Famers at his position. The stated goal of JAWS is to maintain or improve the Hall of Fame's standards by electing players who are at least as good as the average Hall of Famer at those players' positions.

A player's JAWS is calculated by averaging his career WAR with the total WAR from his seven-year peak -- that is, his seven most valuable seasons (consecutive or non-consecutive). This formula allows great players who lack longevity to be judged more favorably than they would by traditional methods.

For non-pitchers, any WAR accumulated at the plate, in the field and on the bases is included, while WAR amassed on the mound is not. This way, typical one-way players are not penalized when compared with the rare Hall of Famers who generated great value as a pitcher and as a hitter, such as Babe Ruth.

Grouping current Hall of Famers by position (using the fielding spot at which a player generated the most WAR in his career) allows for the creation of an average JAWS at each position. These averages serve as the basis for comparisons between non-Hall of Famers and those already enshrined.

To prevent the position-specific JAWS averages from being skewed by small sample sizes (fewer than 300 players are in the Hall altogether, with several positions represented by fewer than 20 players), "Hall of Fame average position players" are added to the formula until the total number of players in a positional group matches that of the most-inducted position (currently right field). These players are given JAWS equal to the average among all non-pitchers in the Hall of Fame.

For example, the Hall of Fame had just 13 third basemen prior to Chipper Jones' election in 2018, compared to 24 right fielders. Accordingly, the positional group used to generate the average JAWS (55.2) among Hall of Fame third basemen included those 13 hot-corner men and 11 "Hall of Fame average position players." Jones himself amassed 85 WAR in his career and 46.6 during his seven most productive seasons, based on WAR. Thus, his JAWS is 65.8.

Source: MLB

Japanese Posting System

Players from Japan's top league -- Nippon Professional Baseball (NPB) -- who do not have the requisite nine years of professional experience to gain international free agency can request to be "posted" for Major League clubs.

Under posting rules that were instituted in the 2018-19 offseason, the "release fee" -- an amount that an NPB club must receive in the event an agreement is reached between a posted player and a Major League club -- depends on the guaranteed value of the contract a posted player signs with a Major League club. All 30 MLB clubs have 30 days to negotiate with a player after he is posted. Typically, players have to be posted between Nov. 1 and Dec. 5. (The "posting window" was pushed back to Nov. 8-Dec. 12 in 2020.)

If no agreement is reached in that timeframe, the player returns to his NPB club for the coming season. He cannot be posted again until the following offseason. Previously, Japanese clubs set a release fee that could be as high as $20 million. Any MLB club that was willing to meet the designated release fee could negotiate with the player for 30 days after the player was posted, but only the club with which the player signed had to pay that release fee. Now, the release fee is determined as follows:

• For Major League contracts with a total guaranteed value of $25 million or less, the release fee will be 20 percent of the total guaranteed value of the contract.
• For Major League contracts with a total guaranteed value between $25,000,001 and $50 million, the release fee will be 20 percent of the first $25 million plus 17.5 percent of the total guaranteed value exceeding $25 million.
• For Major League contracts with a total guaranteed value of $50,000,001 or more, the release fee will be 20 percent of the first $25 million plus 17.5 percent of next $25 million plus 15 percent of the total guaranteed value exceeding $50 million.
• For all Minor League contracts, the release fee will be 25 percent of the signing bonus. For Minor League contracts that contain Major League terms, a supplemental fee will be owed if the player is added to the 25-man roster.
• If a posted player signs a Major League contract that contains bonuses, salary escalators or options, a Japanese team may receive a supplemental fee equal to 15 percent of any bonus or salary escalators actually earned by the player, and/or 15 percent of any option that is exercised.

So if a player signs a Major League contract with a guaranteed value of $100 million, his Japanese team would receive roughly $16.9 million ($5 million for the first $25 million, $4.4 million for the second $25 million and $7.5 million for the final $50 million).

The caveat of the posting system is that foreign-born players are subject to international bonus pool money restrictions unless they are at least 25 years of age and have played as a professional in a foreign league recognized by Major League Baseball for a minimum of six seasons. Under the 2017-21 Collective Bargaining Agreement, each Major League club has a cap between $4.75 million and $5.75 million to spend on the non-exempt foreign-born player pool. Clubs will be able to acquire up to 75 percent of their initial international bonus pool money in the 2017-18 and 2018-19 signing periods and up to 60 percent of their initial pools in subsequent signing periods. This means that a club with an initial pool of $5.75 million can increase its pool total via trade to approximately $10.1 million during the 2017-18 and 2018-19 signing periods.

Examples

The Yankees signed Masahiro Tanaka to a seven-year, $155 million contract -- a sum they paid in addition to a $20 million release fee, which went to the Rakuten Golden Eagles -- following the 2013 season. On the other side of the scale, the Rangers paid a $500,000 release fee to the Yakult Swallows for right-hander Tony Barnette after the 2015 season. Texas then signed Barnette to a two-year, $3.5 million contract, bringing their total investment in him to $4 million.

Source: MLB

Jump

Jump is a Statcast metric that shows which players have the fastest reactions and most direct routes in the outfield. It's defined as: "How many feet did he cover in the right direction in the first three seconds after pitch release?"

The Jump leaderboards may be viewed at Baseball Savant here.

In addition, Jump can be broken down into three components.

  • Reaction: Feet covered (in any direction) in the first 1.5 seconds. Think of it like a way to measure first step.
  • Burst: Feet covered (in any direction) in the second 1.5 seconds. Think of it like a way to measure acceleration.
  • Route: Compares feet covered in any direction to feet covered in the correct direction over the full three seconds.

All of them are measured in "raw feet" but reported in "feet above or below Major League average," for context. ("Average" being slightly different for each play, as each type of play has its own slightly different baseline, based on running back or not, near the wall or not, and the length of time the ball is in the air.) (Note that for seasonal leaderboards, only plays with a 90 percent Catch Probability or harder will be considered; on 'easy' plays, there's often no jump or direct route even required.)

Source: MLB

K

K

A "K" is a strikeout.

Origin

Referring to a strikeout as a K goes all the way back to the mid-19th century -- when journalist Henry Chadwick began developing baseball's first scorecard. His original system used only single letters, and Chadwick couldn't use "S" for "struck" (the preferred term of the time period) because it had already been taken by "sacrifice." So instead, he decided to go with what he thought was the word's most memorable sound: the letter K.

Source: MLB

Knuckle-curve (KC)

The knuckle-curve is one of baseball's greatest paradoxes, given that a curveball is defined by its spin and a knuckleball is defined by its lack thereof. Still, the knuckle-curve produces the desired effect of the two pitches -- a slow, curveball break mixed with the unpredictable fluttering of the knuckleball.

Very few pitchers have mastered the knuckle-curve, and those that throw it generally don't do so often. It's a deceptive weapon for those pitchers, often stashed away until they think a hitter will be fooled by it.

Grip

There are a few different ways to grip and throw a knuckle-curve. The basic premise is that at least one of the pitcher's fingers is bent while holding the ball -- like a knuckleball -- while the pitcher maintains the snap of the wrist that is synonymous with a curveball.

Think of the pitch as a spectrum between a knuckleball and a curveball. For pitchers who emphasize the curveball aspects of the pitch (bending one finger so that a knuckle is on the ball), a knuckle-curve is basically just a curveball that spins and moves slower. And for pitchers who emphasize the knuckleball aspects of the pitch (gripping the ball like a knuckler, while ever-so-slightly snapping the wrist),

a knuckle-curve is basically just a knuckleball that spins more and moves faster.

Origin
Because some knuckle-curves are so close to a regular knuckleball and others are so close to a regular curveball, the pitch has existed for years while simply being indentified as one or the other. It's quite possible that Ed Summers, who pitched for the Tigers until 1912, was the first to throw the knuckle-curve regularly, as he was well known for the varied deliveries and movement on his knuckleballs.

In A Call

"slow curve," "fluttering curve," "dry spitter"

Source: MLB

Korean Posting System

Players from Korea's top league -- the Korea Baseball Organization (KBO) -- who do not have the requisite nine years of professional experience to gain international free agency can request to be "posted" for Major League clubs. When a KBO club posts a player, all 30 Major League clubs are allowed to negotiate with the player and his representative for a specific period of time. During the 2020-2021 offseason, that window begins on Nov. 10 and ends Dec. 14, according to Jee-ho Yoo of Yonhap News. To sign a posted player, an MLB team must pay a release fee to the KBO club, calculated based on the amount of his guaranteed contract. For Major League contracts, the KBO team receives a payment equal to 20% of the first $25 million in guaranteed value, 17.5% of the next $25 million, and 15% on all amounts above $50 million. When the posted player signs a Minor League contract, the KBO team receives a payment equal to 25% of the signing bonus. Under KBO rules, a club is allowed to post only one player at a time and cannot allow more than one player to leave via the posting process per offseason.

The caveat is that foreign-born players are subject to international bonus pool money restrictions unless they are at least 25 years of age and have played as a professional in a foreign league recognized by Major League Baseball for a minimum of six seasons. Under the 2017-21 Collective Bargaining Agreement, each Major League club has a cap between $4.75 million and $5.75 million to spend on the non-exempt foreign-born player pool. For the 2020-2021 signing period, clubs are able to acquire up to 60 percent of their initial international pool. Thus, a club with an initial pool of $5.75 million may make trades that increase its pool to a maximum of $9.2 million.

Source: MLB

L

Lat Strain

The latissimus dorsi is the broadest muscle of the back. It extends from the top of the hip to the lower six thoracic vertebrae in the mid-back and up to the top of the humerus -- the bone in the upper arm that forms the ball of the ball-and-socket shoulder joint -- at the front of the shoulder.

Like all muscle strains, the lat strain is broken down into three grades. Grade 1 is a mild strain, Grade 2 is a moderate strain and Grade 3 is a severe strain in which the muscle ruptures.

Typical recovery time

Recovery time varies depending on the strain, with Grade 1 strains typically requiring 2-3 weeks and Grade 2 strains usually taking at least a month. Grade 3 strains often require surgery, however, and can come with considerably longer recovery periods.

Source: MLB

Late-inning Pressure Situation (LIPS)

Late-inning pressure situations are defined as any at-bat in the seventh inning or later where the batter's team trails by three runs or fewer, is tied or is ahead by only one run. If the bases are loaded and the batting team trails by four runs, this also counts as a late-inning pressure situation.

Origin

LIPS was developed by the Elias Sports Bureau in 1985 in an attempt to answer the question, "Do clutch hitters exist?"

Source: MLB

Launch Angle (LA)

Launch Angle represents the vertical angle at which the ball leaves a player's bat after being struck. Average Launch Angle (aLA) is calculated by dividing the sum of all Launch Angles by all Batted Ball Events.

As a guideline, here are the Launch Angles for different types of contact:

Ground ball: Less than 10 degrees
Line drive: 10-25 degrees
Fly ball: 25-50 degrees
Pop up: Greater than 50 degrees
Hitters can be evaluated by their average Launch Angle, but the tool is generally more valuable in discussing pitchers. In the case of pitchers, the statistic is referred to as "average Launch Angle Against" (aLAA), and it does a good job of telling us what type of pitcher is on the mound. Is he a fly-ball pitcher? Is he a ground-ball pitcher? Average Launch Angle Against attempts to answer those questions.

Generally, pitchers who can limit their Launch Angle Against (keeping the ball on the ground) are more successful, because they are the most adept at avoiding home runs and extra-base hits, which come almost exclusively via fly balls and line drives.

Average Launch Angle tells us about the tendencies of hitters, too -- with a high average Launch Angle indicating a fly-ball hitter, and a low average Launch Angle indicating a ground-ball hitter. On average, fly-ball hitters generally drive in more runs than ground-ball hitters.

In A Call

"The ball left his bat at a X degree angle"

Source: MLB

Lead Distance (LEAD)

Lead Distance represents the distance between the base and the baserunner's center of mass as the pitcher makes his first movement -- either to home or to the base on a pickoff attempt.

Lead Distance might be the most overlooked aspect of stealing bases. Certain baserunners -- those who can react quickest to a pitcher's move -- take leads that are longer than an average player. In doing so, the distance between the base stealer and the base he is trying to swipe is cut down.

Sure, Maximum Speed, Acceleration, a catcher's Pop Time and a pitcher's delivery all have a major impact on stolen bases, too. But on a bang-bang play, the runner's initial Lead Distance can sometimes make all the difference. (The same can hold true even when the runner is not attempting to steal, but rather when there is a close play at the next base after the ball is put in play.)

In A Call

"He's X feet off the base"

Source: MLB

Left Fielder

The left fielder covers the left portion of the outfield grass (when viewing the field from home plate).

Speed and range for a left fielder aren't considered as crucial as they are for a center fielder. Additionally, left fielders typically don't require as strong of a throwing arm as center fielders or right fielders, as throws from left field to second, third and home -- particularly third -- are not as long as throws from center field and right field.

Source: MLB

Left On Base (LOB)

Left on base can be viewed as both an individual statistic or as a team statistic.

In an individual batter's case, it refers to how many men remain on base after that batter makes an out at the plate, as the batter has failed to do his job to score those runners -- or at least put himself in a position to score.

In a team's case or in an individual pitcher's case, it refers to the number of men who remain on base at the end of an inning.

LOB can be a very circumstantial statistic on a game-by-game basis. But the best teams are usually good at finding a way to get runners home once they've reached base.

In A Call

"stranded," "runners stranded," "ducks left on the pond"

Source: MLB

Leverage Index (LI)

Created by Tom Tango, Leverage Index measures the importance of a particular event by quantifying the extent to which win probability could change on said event, with 1.0 representing a neutral situation.

For instance, if a team trailing by three runs had the bases loaded with two outs in the eighth inning, the ensuing plate appearance would register an LI above 1.0. This is because the outcome of the game could dramatically change on that one plate appearance. Conversely, if a team trailing by four runs has a man on first with one out in the top of the ninth inning, the ensuing plate appearance would register an LI below 1.0.

Why it's useful

LI can be used to more easily pinpoint the pivotal moments in a particular game and determine how often players face high-leverage situations.

Source: MLB

Line-drive Rate (LD%)

Line-drive rate represents the percentage of balls hit into the field of play that are characterized as line drives. Each ball that is hit into the field of play is characterized as a line drive, a fly ball, a ground ball or a pop-up. Line-drive rate can be used as a metric to evaluate both hitters and pitchers.

In A Call

"line-drive percentage"

Source: MLB

Lisfranc Injury

The Lisfranc joint complex, named for the French surgeon who first described it in the 1800s, includes the five metatarsal bones along with the tendons and ligaments that connect the mid-foot to the forefoot and form the arch at the top of the foot. Ligaments and tendons in this area can be sprained, and the bones can be fractured. Lisfranc injuries can be the result of a trauma, such as a collision, or they can be caused indirectly by a sudden rotational force in the mid-foot.

Typical recovery time

If there are no fractures and the ligaments are not completely torn, a player will typically wear a non-weightbearing cast for up to six weeks before beginning a rehab program. However, most Lisfranc fractures require surgery to realign the joints and ensure the bones heal in the proper position. Following surgery, full recovery can take up to six months.

Source: MLB

Loss (L)

A pitcher receives a loss when a run that is charged to him proves to be the go-ahead run in the game, giving the opposing team a lead it never gives up. Losses are almost always paired with wins when used to evaluate a pitcher, creating a separate pitching term known as win-loss record.

Win-loss record took on a greater importance in the past for a different reason. In the time when pitchers routinely pitched complete games, bullpens were rarely at fault for losses. But today's specialization of relief pitchers has led to starters pitching fewer innings.

A starting pitcher does not necessarily receive a loss every time his team loses -- even if he exits the game with his team trailing. In such instances, if his team ties the game or takes the lead before eventually losing, it will be the pitcher who put the go-ahead run on base who takes the loss.

In A Call

"took the L," "losing pitcher"

Source: MLB

M

MLB Draft League

Announced in November 2020, the MLB Draft League will give eligible prospects a chance to showcase their abilities and gain exposure prior to the MLB Draft.

The league is expected to include a 68-game regular season with an annual All-Star break centered around the Draft, which will take place in July starting in 2021 after previously being held in June.

The Mahoning Valley Scrappers, State College Spikes, Trenton Thunder, West Virginia Black Bears and Williamsport Crosscutters have been announced as founding members. These teams were previously affiliated with Minor League Baseball but were reassigned as part of MLB's reorganization of Minor League Baseball in November 2020.

Meanwhile, the independent American Association, Frontier League, Atlantic League and Pioneer League have been designated as Partner Leagues of MLB, and the Appalachian League has been converted into a collegiate wood-bat summer league. The Pioneer League and Appalachian League were previously Minor League Baseball affiliates as well.

Source: MLB

Maddux

A Maddux describes a start in which a pitcher tosses a complete-game shutout on fewer than 100 pitches. Named after Hall of Famer Greg Maddux, the term was coined by baseball writer Jason Lukehart.

Since 1988, the first year accurate pitch-count data is available, Maddux ranks first in the Majors with 13 such starts during the regular season. Nobody else has thrown more than seven.

Source: MLB

Magic Number (MN)

In baseball, the phrase "magic number" is used to determine how close a team is to making the playoffs or winning the division. It becomes prominent every year in September as teams begin closing in on clinching.

A team's magic number represents the combination of wins needed by that team and losses by its closest competitor to clinch a given goal. Every time a team wins, its magic number decreases by one. Similarly, every time that team's closest competitor for the division (or Wild Card) loses, the magic number also decreases by one.

The exact formula is: Games remaining +1 - (Losses by second place team - losses by first place team)

If a new second-place team emerges, the magic number adjusts to that new second place team. The second-place team (in terms of total losses) must always be used as the barometer for the first-place team's magic number.

Origin

The first known usage of the magic number came during the pennant race between the Yankees and Red Sox during the 1947 season. An article in the Sept. 12, 1947, edition of the Washington Post stated: "The Yankees reduced the magic number to four. That is the combination of games the Yankees must win or the Red Sox must lose in order to insure the flag for the Yankees."

In A Call

"playoff number," OR "elimination number" and "tragic number" when referring to how close teams are to elimination

Source: MLB

The official logo of Major League Baseball was designed by Jerry Dior in 1968, when MLB commissioned the marketing firm Dior worked at to create a logo for the centennial celebration of professional baseball, set to take place in 1969. The logo first appeared on uniforms during the 1969 season.

The ubiquitous design includes a white silhouette of a batter -- popularly thought to be Hall of Famer Harmon Killebrew -- flanked by a backdrop of blue and red. Dior has said that he did not model the logo after any one player and instead made it intentionally ambiguous in every way, including the batter's side of the plate.

Source: MLB

Manager

Field managers are responsible for writing out the daily lineup and making in-game tactical decisions (e.g. pitching changes and decisions regarding pinch-hitting, pinch-running and defensive replacements). Often viewed as a face of his franchise, managers also play a crucial role in interacting with the media before and after games and managing the atmosphere in the clubhouse.

Managers are often former players, as said experience can help them relate to current players by virtue of shared experiences and familiarity with the innerworkings of the clubhouse setting. But even with this in mind, managers still take input from the front office -- scouts and data analysts -- in an effort to make optimal game-management decisions.

Managers -- also commonly referred to as "skippers" -- are also responsible for issuing instant-replay challenges, and they will occasionally argue with the umpiring staff in protest of a call on the field. Managers are known to insert themselves between an upset player and an umpire in order to prevent the player from being ejected from the game.

Source: MLB

Manager Challenge

Each club receives two manager challenges to start each All-Star Game, postseason game and Divisional or Wild Card tiebreaker game, and one manager challenge to start every other game. All reviews are conducted at the Replay Command Center, which is located at Major League Baseball Advanced Media headquarters in New York, by replay officials -- full-time Major League umpires who work shifts at the Replay Command Center in addition to their on-field work. Replay officials review all calls subject to replay review and decide whether to change the call on the field, confirm the call on the field or let stand the call on the field due to the lack of clear and convincing evidence.

A manager may challenge as many reviewable calls within a single play as he desires using one challenge. The club retains its manager challenge if the replay official overturns any challenged call (even if he upholds other challenged calls), and loses its manager challenge if no calls are overturned. Once a club has exhausted its available manager challenge(s), it will no longer have the ability to challenge any additional play or call in the game.

A manager has a 20-second time limit (as of 2020; previously was 30 seconds) to inform the umpire (by verbal communication or hand signal) whether he wishes to use his manager challenge to invoke replay review, and the challenge may not be rescinded once it has been exercised.

Both managers may challenge different reviewable calls within the same reviewable play, and the replay official shall review the challenged calls in the order in which the calls occurred during the game. If the decision of the replay official on an earlier reviewable call renders moot a later reviewable call, the subsequent call shall not be reviewed and that club shall not be charged with the challenge.

The manager must ensure that the umpire knows the specific calls for which he is seeking replay review, but the manager need not state the reason for his belief that the call was incorrect. Moreover, the replay official shall have no authority to review any calls other than those included in a manager's challenge or those accepted for review by the crew chief.

History of the rule

Major League Baseball instituted replay review -- to be used at the umpire's discretion -- on disputed home run calls (fair or foul, in or out of the ballpark, fan interference) on Aug. 28, 2008.

Replay review was expanded starting in the 2014 season, giving managers one challenge to start the game and allowing them to challenge two times in total provided the first challenge resulted in an overturned call. In addition, a much wider range of calls were made subject to review.

Replay review was modified again in 2015, permitting managers to retain their challenge after every overturned call; allowing them to signal for a challenge during an inning without approaching the umpire on the field; and providing two challenges for any All-Star Game, postseason game and Divisional or Wild Card tiebreaker game. The list of calls that were subject to review was also expanded again in 2015 and 2016.

Prior to a 30-second time limit being implemented for the 2017 season, a manager challenge could be exercised up until the commencement of the next play or pitch. On-field personnel were not permitted to intentionally delay the game in order to provide their club with additional time to challenge a play. In the case of a play that resulted in a third-out call, a manager needed to immediately run onto the field to notify an umpire that the club was contemplating a challenge. After entering the field, a manager then had up to 30 seconds to invoke the challenge. The 30-second timeframe was shortened to 20 seconds prior to the 2020 season.

Source: MLB

Mendoza Line

The "Mendoza Line" is a .200 batting average.

Origin

The Mendoza Line was a term coined by a teammate of Mario Mendoza on the 1979 Mariners -- usually credited to Tom Paciorek or Bruce Bochte -- as a joke on the light-hitting shortstop, who typically carried an average around .200 (though he actually finished with a career mark of .215).

Source: MLB

Minor League Options

Players on a 40-man roster are given three Minor League "options." An option allows that player to be sent to the Minor Leagues ("optioned") without first being subjected to waivers. Players who are optioned to the Minors are removed from a team's active 26-man roster but remain on the 40-man roster.

A player who is on the 40-man roster but does not open the season on the 26-man roster or the injured list must be optioned to the Minor Leagues. Once an optioned player has spent at least 20 days in the Minors in a given season, he loses one of his options. Only one Minor League option is used per season, regardless of how many times a player is optioned to and from the Minors over the course of a given season. Out-of-options players must be designated for assignment -- which removes them from the 40-man roster -- and passed through outright waivers before being eligible to be sent to the Minors.

Players typically have three option years, but those who have accrued less than five full seasons (including both the Major and Minors) are eligible for a fourth if their three options have been exhausted already. For the purposes of this rule, spending at least 90 days on an active Major League or Minor League roster during a given season counts as one full season. Players also earn a full season if they spend at least 30 days on an active Major League or Minor League roster AND their active-roster and injured-list time amounts to at least 90 days in a given season.

Upon being optioned to the Minor Leagues, a position player must remain there for a minimum of 10 days before he is eligible to be recalled to the Major League roster. For pitchers, the minimum is 15 days. If a player is serving as the 27th man for a doubleheader or replacing a player who has been placed on the injured list, there is no minimum number of days for which the optioned player must remain in the Minors.

A player's option years do not need to be used in succession. Any player with fewer than five years of Major League service time and an option year remaining can be optioned to the Minor Leagues. Players with more than five years of service time must consent to being optioned.

Source: MLB

Mound Visit

The members of the coaching staff (including the manager) can make one mound visit per pitcher per inning without needing to remove the pitcher from the game. If the same pitcher is visited twice in one inning, the pitcher must be removed from the contest. These mound visits are limited to 30 seconds, starting when the manager or coach has exited the dugout and been granted time by the umpire. The mound visit is considered to be concluded once the manager or coach leaves the 18-foot circle surrounding the pitching rubber, though they are permitted to temporarily leave that area to notify the umpire of a substitution. In that case, the manager or coach can then return to the mound without it being counted as two mound visits.

Mound visits are limited to five per team per nine innings, with teams receiving an additional visit for every extra inning played. Any manager, coach or player visit to the mound counts as a mound visit under this rule, though visits to the mound to clean cleats in rainy weather, to check on a potential injury or after the announcement of an offensive substitution are excepted. Normal communication between a player and pitcher that doesn't require either to vacate his position on the field doesn't count as a visit. If a team is out of visits, the umpire will have discretion to grant a brief visit at the catcher's request if a cross-up has occurred between the pitcher and catcher.

History of the rule

Mound visits had no time limit prior to the 2016 season, when Major League Baseball began limiting visits by managers and coaches to 30 seconds. The rule limiting each team to six mound visits per nine innings was instituted prior to the 2018 campaign and changed to five per nine innings prior to the 2019 season. Previously, the only restriction on the number of mound visits each team could make was the one requiring a pitcher to be removed if he was visited twice in one inning.

Source: MLB

Mutual Option

A mutual option is an optional year at the end of a contract. In order for the optional year to become guaranteed, both parties must agree to exercise the option.

Mutual options are very rarely exercised. If a player enjoys a strong season, the club will often exercise its half of the option in the hope of retaining the player on a one-year deal. However, the player, fresh off a high-quality performance, will likely wish to test the open market in search of a larger guarantee on a one-year or a multi-year contract. Likewise, a player whose stock is down might exercise his half of the option rather than test free agency, but his club may no longer view him as worth that salary.

Example

Though rare, the mutual option has been exercised in the past. Planning to retire following the 2015 season, Aramis Ramirez agreed to exercise his half of a $14 million mutual option with the Brewers. Perhaps viewing $14 million as a fair salary for a player of Ramirez's ability, Milwaukee exercised its half of the option as well.

Source: MLB

N

Neighborhood Play

The "neighborhood play" is a colloquial term used to describe the leeway granted to middle infielders with regards to touching second base while in the process of turning a ground-ball double play. Though it is not explicitly mentioned in the rulebook, middle infielders were long able to record an out on the double-play pivot simply by being in the proximity -- or neighborhood -- of the second-base bag. The maneuver had been permitted for safety purposes, as it allowed the pivot man to get out of the way of the oncoming baserunner as quickly as possible.

But via a rule change instituted before the 2016 season, the neighborhood play is now reviewable by instant replay. That means middle infielders must touch the second-base bag while in possession of the ball in order to ensure the out is made on a ground-ball double play. In order to protect the middle infielders, Major League Baseball also amended the sliding rules for baserunners.

History of the rule

The amendments to the sliding rules were implemented after a 2015 season in which a number of middle infielders were injured by sliding baserunners while covering second base. In accordance with the rule change, MLB determined that questionable slides and the neighborhood play would both now be reviewable by instant replay.

Source: MLB

No-trade Clause

A no-trade clause is a contractual clause that allows players to veto trades to certain teams. No-trade clauses are often worked into contract extensions and free-agent contracts as a perk for the players signing such deals.

Some contracts include partial no-trade clauses, which allow a player to block trades to a specified list of teams. In the case of a partial no-trade clause, the player that agrees to such a clause will sometimes be allowed to update on a yearly basis the teams to which he cannot be traded without his consent. In other instances, teams will concede to a full no-trade clause that allows the player in question to block a trade to all 29 other teams.

Beyond that, a player that has accumulated 10 years of Major League service time and has spent the past five consecutive seasons of that service time with one team gains the right -- termed 10-and-5 rights -- to veto a trade to any team.

Examples

Per the terms of his contract extension signed in 2011 -- which spans the 2016-20 seasons -- Brewers outfielder Ryan Braun was given the ability to block trades to 23 of the 29 other Major League teams. On the other end of the spectrum, Twins right-hander Ricky Nolasco agreed to a very limited no-trade protection as part of his four-year, $49 million contract with Minnesota. As of December 2015, Nolasco was reportedly able to veto trades to just three teams.

The Reds' Brandon Phillips reportedly invoked his 10-and-5 rights two separate times between the 2015 and 2016 seasons, blocking trades that would have sent him to the D-backs and to the Nationals.

The Nationals had interest in trading for Phillies closer Jonathan Papelbon in July 2015, but Papelbon had a no-trade provision in his contract that allowed him to block a deal to 17 clubs -- including Washington. Papelbon also had a vesting option for 2016 in his contract with Philadelphia that would be exercised if he finished 48 games. As a means of enticing the right-hander to waive the no-trade clause, the Nationals offered to exercise that vesting option in advance, and Papelbon agreed to a slightly reduced rate of $11 million as a compromise. With those roadblocks worked out, the Nationals traded Minor League right-hander Nick Pivetta to the Phillies in exchange for Papelbon to complete the deal.

Source: MLB

Non-guaranteed Contract

Players who are on arbitration (unless specified at the time of the agreement), Minor League or split contracts are not fully guaranteed their salaries.

Players on arbitration contracts who are cut on or before the 16th day of Spring Training are owed 30 days' termination pay (based on the prorated version of his agreed-upon arbitration salary). A player cut between the 16th day and the end of Spring Training is owed 45 days' termination pay (based on the prorated version of his agreed-upon arbitration salary). The arbitration salary becomes guaranteed if the player is on the 25-man roster when the season begins.

A player on a split or Minor League contract will earn the prorated portion of his Major League salary for time spent on the Major League roster. Clubs can also sign players to non-guaranteed contracts but still place them on the 40-man roster. Those contracts become guaranteed upon the player making the Major League roster out of Spring Training, but he may also be cut prior to Opening Day. Such cases are identical to arbitration contracts in that the club would owe either 30 or 45 days' worth of termination pay, depending on the time at which the player is released.

Examples

Prior to the 2016 season, the Angels signed Craig Gentry to a split contract and Al Alburquerque to a non-guaranteed contract. Each player was added to the 40-man roster, but neither player's contract was fully guaranteed at the time of the signing. Both contracts were contingent upon the players making the Major League roster in Spring Training.

Source: MLB

Non-roster Invite (NRI)

A non-roster invite (NRI) is an invitation for a player who is not on a club's 40-man roster to attend Major League camp in Spring Training and compete for a roster spot. Clubs can extend NRIs to their upper-level Minor Leaguers and also include NRIs in Minor League contracts given to free agents in the offseason.

Example

In February 2015, the Kansas City Royals signed left-hander Franklin Morales to a Minor League contract with an invitation to Major League Spring Training. Morales attended Spring Training with the club and won a roster spot with a strong performance. He went on to post a 3.18 ERA in 62 1/3 relief innings for the eventual World Series champions.

Source: MLB

Non-tendered

When a club "non-tenders" a player, it declines to give that player a contract for the upcoming season, thereby immediately making him a free agent. Players on the 40-man roster with fewer than six years of Major League service time must be tendered contracts each offseason by a set deadline -- typically a date in early December -- or non-tendered and released to the free-agent pool.

In many instances, a club will non-tender a player because it feels the raise he will receive in arbitration would be greater than his on-field value. In other cases, a club will non-tender a player simply to clear a spot on the 40-man roster -- even if that player isn't due much more than the league minimum the following season.

Examples

Henderson Alvarez was due to receive $4 million or more in arbitration following the 2015 campaign, in which he made just four starts before undergoing season-ending shoulder surgery. Rather than tender a contract to a player who missed considerable time, the Marlins non-tendered Alvarez in December 2015.

Also in December 2015, the Astros elected to non-tender first baseman Chris Carter rather than pay him a raise on his $4.175 million salary from the prior season.

Source: MLB

Number of Pitches (NP)

A pitcher's total number of pitches is determined by all the pitches he throws in live game action, including strikes, unintentional balls and intentional balls.

The number of pitches thrown by a pitcher is a very important number in any baseball game. It's often used to determine when a pitcher might begin to get tired. Conversely, it often benefits a hitter to face a high number of pitches, because the more pitches he sees, the more likely he is to wear down a pitcher.

Origin

Pitch counts became prominent for pitchers in the 1980s. Many games taking place before then do not have records of the number of pitches thrown, but pitch counts (and innings-pitched totals for individual pitchers) were much higher before then.

In A Call

"pitch count," "total pitches," "pitches thrown," "tosses"

Source: MLB

O

Oblique Strain

The oblique muscles lie alongside the rectus abdominis muscles -- the ones that make up the "six pack" -- and are responsible for core control and rotation. The internal oblique sits under the external oblique and is the most commonly injured abdominal or core muscle in baseball because it is the most activated core muscle during hitting and throwing.

Like all muscle strains, the oblique strain is broken down into three grades. Grade 1 is a mild strain, Grade 2 is a moderate strain and Grade 3 is a severe strain in which the muscle ruptures.

Typical recovery time

While some mild oblique strains can be resolved in just a few days, severe strains can require surgery with a recovery time of 3-4 months. In 2017, former Dodgers athletic trainer Stan Conte of Conte Injury Analytics teamed with the Hospital for Special Surgery in New York City and Major League Baseball to further examine the impact of oblique strains on injured MLB players. Using MLB's Health and Injury Tracking System (HITS), the study ultimately revealed that hitters typically take 27 days to recover from a Grade 1 strain, while pitchers typically take as many as 35 days.

Source: MLB

Obstruction

Obstruction describes an act by a fielder, who is not in possession of the ball or in the process of fielding it, that impedes the baserunner's progress.

If a play is being made on the obstructed baserunner, the ball is ruled dead and the umpire can place all runners on the base he determines they would have reached without the obstruction. If no play is being made on the obstructed runner, the umpire will allow the play to progress until its natural conclusion and then impose any penalties he sees fit to nullify the act of obstruction.

Source: MLB

Official Scorer

The official scorer is the person appointed to observe from the press box and record the outcome of everything that happens during a game, and to make judgment calls that affect the official record of said game. The official scorer files a report after each game for documentation purposes.

The most common judgment call an official scorer makes is whether a batter reached base on a hit or an error. Other rulings made by the official scorer include whether a pitch that goes past the catcher is a wild pitch or a passed ball, and which reliever is credited with a win when the starting pitcher does not go five innings but leaves with a lead that his team doesn't relinquish.

The official scorer is permitted to change a judgment call for up to 24 hours after a game concludes or is suspended. A player or team can request that the executive vice president of baseball operations review a call in which said player or team participated. This request must come within 72 hours after the conclusion or suspension of that game, or 72 hours after the official scorer's call in the event a postgame change is made.

Source: MLB

Oliver

Oliver is a system of player projections developed by Brian Cartwright and used by The Hardball Times. For projecting returning Major League players, it uses a somewhat basic formula: Three years of player data with the most recent years weighted heavier, while also factoring age and regression to the mean.

In that way, Oliver is not unlike the Marcel projection system, which is known to be one of the most basic projection models. But where Oliver differs is in its method for projecting Minor League players' transitions to the Majors -- or in projecting younger players with minimal big league experience.

Whereas Marcel simply uses league averages for those players -- and other projection systems weigh trends from each Minor League level equally -- Oliver uses its own formula to assess Minor League data.

Source: MLB

On-base Plus Slugging (OPS)

OPS adds on-base percentage and slugging percentage to get one number that unites the two. It's meant to combine how well a hitter can reach base, with how well he can hit for average and for power.

It can also be used in evaluating pitchers; when used in that context, it is referred to as OPS against.

Source: MLB

On-base Plus Slugging Plus (OPS+)

OPS+ takes a player's on-base plus slugging percentage and normalizes the number across the entire league. It accounts for external factors like ballparks. It then adjusts so a score of 100 is league average, and 150 is 50 percent better than the league average.

For example, Miguel Cabrera's .895 OPS in 2014 was 50 percent better than the MLB average after being adjusted for league and park factors. As a result, his OPS+ was 150.

The formula

(OPS / league OPS, adjusted for park factors) x 100.

Why it's useful

OPS does not tell you how much a player was affected by factors such as his home ballpark's dimensions or altitude. OPS+ attempts to adjust for those factors to give you a context-neutral number.

Source: MLB

Opener

An "opener" is a pitcher -- normally a reliever -- who starts a game for purposes of matching up against the top of the opponent's lineup in the first inning, which has traditionally been the highest-scoring inning, before being relieved by a pitcher who would otherwise function as a starter. This allows for a team to counter its opponent's first three batters with the pitcher it feels has the best chance for success against them.

The second pitcher (often called the headliner) usually pitches the bulk of the game, potentially relieved in the later innings due to high-leverage situations or high pitch count.

Source: MLB

Ordinary Effort

Ordinary effort refers to the effort that a fielder of average skill at a specific position should exhibit on a play, with due consideration given to the conditions of the playing field and the weather. Umpires must use that standard when calling infield fly plays, and the official scorer uses it to judge what constitutes an error, a wild pitch, a passed ball and a sacrifice.

Source: MLB

Out (O)

One of baseball's most basic principles, an out is recorded when a player at bat or a baserunner is retired by the team in the field. Outs are generally recorded via a strikeout, a groundout, a popout or a flyout, but MLB's official rulebook chronicles other ways -- including interfering with a fielder -- by which an offensive player can be put out.

For every out that is recorded by the defensive team, a putout is given to a fielder and a third of an inning pitched is awarded to the pitcher. Three outs are required to retire the side in an inning.

In A Call

"down," "retired," "away," "gone," "put out"

Source: MLB

Outfield Assist (OFA)

An outfielder records an assist when he throws the ball into the infield and an out is recorded as a result. Outfield assists are one of the most commonly referenced types of assists.

Outfield assists often result from throws directly to a base, without the help of an infielder. However, if a relay throw is needed or if an infielder cuts the throw off to get an out at a different base, the outfielder is still credited with an assist. Similarly, if one outfielder touches the ball before another outfielder throws to the infield for an out, both outfielders are awarded an assist.

In A Call

"nailed," "thrown out," "hosed"

Source: MLB

Outright Waivers

A club attempting to remove a player from the 40-man roster and send him to the Minor Leagues must first place that player on outright waivers, allowing the 29 other Major League clubs the opportunity to claim him. The claiming club assumes responsibility for the remaining money owed to the claimed player, who is placed on his new club's 40-man roster. Should the player clear waivers, he can be sent to any Minor League affiliate the club chooses. Outright waivers are also used when clubs wish to remove a player who is out of Minor League options from the 26-man roster (it was 25, prior to 2020) by sending him to the Minors.

If a player has more than three years of Major League service time or was previously outrighted in his career (by his current club or another club), he is eligible to reject the outright assignment and instead opt for free agency. Players with more than three but less than five years of Major League service time must forfeit any remaining guaranteed money on their contract if they reject an outright assignment. Conversely, those with five or more years of Major League service time are still owed any guaranteed money remaining on their contract, should they elect free agency following an outright.

Source: MLB

Outs Above Average (OAA)

Outs Above Average (OAA) is a range-based metric of skill that shows how many outs a player has saved. Prior to 2020, OAA was an outfield-only metric. But it has been expanded to include infielders. OAA is calculated differently for outfielders and infielders (details below).

Outfielders

Outs Above Average for outfielders starts with Catch Probability, which takes the distance an outfielder must go, the time he has to get there, and the direction he travels to put a percentage of catch likelihood on each individual batted ball. OAA for outfielders is the season-long cumulative expression of each individual Catch Probability play. For example, if an outfielder has a ball hit to him with a 75 percent Catch Probability -- that is, one an average outfielder would make three-quarters of the time -- and he catches it, he'll receive a +.25 credit. If he misses it, he'll receive -.75, reflecting the likelihood of that ball being caught by other outfielders.

Adding up credit for every play made or not made contributes to a seasonal Outs Above Average number. In 2019, Victor Robles led MLB outfielders with +23 OAA.

In addition, the leaderboards show columns for "Expected Catch Percentage," "Actual Catch Percentage," and "Catch Percentage Added," providing the ability to see how a player has performed on a rate basis.

• Expected Catch Percentage shows how many plays an average outfielder would be expected to come up with based on the difficulty of the batted balls hit to the outfielder in question. Of the outfielders with at least 150 chances in 2017, Mike Trout's Expected Catch Percentage of 89 was the highest, meaning an average outfielder catches 89 percent of the balls Trout saw. This shows he got the least challenging opportunities sent his way, while Norichika Aoki, at 77 percent, got the toughest.

• Actual Catch Percentage shows the production of the actual fielder on the balls hit his way. Given the difficulty of batted balls, Trout would be expected to make the catch 89 percent of the time, but in actuality, he made the catch 88 percent of the time.

• Catch Percentage Added shows the difference between the Expected and Actual numbers. For example, Heyward and Ben Gamel were each given the same difficulty of opportunities, being expected to catch 86 percent. But with an Actual Catch Percentage of 90, Heyward added four points of value. Meanwhile, Gamel's Actual Catch Percentage was 83, so he subtracted three points of value. Heyward was seven points more valuable on a rate basis than Gamel, and +18 (comparing his +10 to Gamel's -8) Outs Above Average on a cumulative basis.

Infielders

Outs Above Average for infielders takes the following factors into account.

• How far the fielder has to go to reach the ball ("the intercept point").
• How much time he has to get there.
• How far he then is from the base the runner is heading to.
• On force plays, how fast the batter is, on average. (A runner's average Sprint Speed is used in the calculation, rather than his Sprint Speed on that particular play. For new players with no data, a league-average -- 27 ft/sec -- score is used; once the player qualifies for the leaderboard, all of his previous plays are re-run.)

The Statcast technology allows us to know exactly where each fielder stands, which is helpful in a baseball world where shifting and out-of-position defenders are commonplace. What that means is that every tracked play is accounted for, regardless of if the third baseman is standing in his regular spot, at shortstop or in short right field. It allows you to know exactly "how far" and "how much time," regardless of shifts. It also allows for an OAA breakdown by fielder role.

For example, Nolan Arenado was +17 OAA in 2019, all coming as a third baseman because he played every single inning of his season at third base. But that doesn't mean he was always standing at third base. Due to shifting, Arenado's +17 actually breaks down into +14 OAA where third basemen typically play, and +3 OAA where shortstops play.

Javier Baez led all infielders with +19 OAA in 2019. His breakdown: +17 where shortstops typically play, and +2 where second basemen play, even though he technically was never listed on the lineup card as a second baseman in 2019.

Additional resources

• Statcast introduces Outs Above Average metric
• Statcast Outs Above Average metric expanded to include infielders

Source: MLB

P

Pace of Play

A number of changes have been implemented to improve the pace of play since the 2014 season.

The batter's box rule -- which requires hitters to keep one foot in the box during their time at bat unless one of a group of exceptions occurs -- has been more strictly enforced since the 2015 season.

Also in 2015, timers were installed in Major League stadiums to measure the break time between innings and pitching changes. MLB lowered the time between innings to 2 minutes for local broadcasts and nationally televised games in 2019. MLB had instituted times of 2 minutes, 5 seconds for local broadcasts and 2 minutes, 25 seconds for nationally televised games in 2016, decreasing these times by 20 seconds from where they were previously. Prior to the 2018 season, MLB established a separate time of 2 minutes, 55 seconds for tiebreaker and postseason games.

As of 2018, the umpire's signal for the final warmup pitch comes at the 25-second mark and the pitcher must throw it before the clock hits 20. The batter will be announced at the 20-second mark and the pitcher must begin his windup to throw the first pitch of the inning within the five seconds before the clock hits zero. The pitcher can take as many warmup pitches as he wants within these countdown parameters.

For between-innings breaks, the timer begins when the final out of the inning is recorded, with several exceptions. If the pitcher is on base, on deck or at bat when the inning ends, the timer begins when the pitcher leaves the dugout for the mound. If the catcher is on base, on deck or at bat when the inning ends, the timer begins when the catcher enters the dugout (another catcher can begin warming up the pitcher). If the final out of the inning is subject to replay, the timer begins when the umpire signals the out. And for any extended between-innings event previously approved by the Office of the Commissioner (such as the playing of "God Bless America"), the timer begins at the conclusion of the event.

The timing clock also applies to pitching changes and begins as soon as the relief pitcher crosses the warning track (or the foul line for on-field bullpens). Players can be excused from these time limits if a delay in normal warmup activities occurs due to no fault of the players, or the umpire believes a player would be at legitimate risk of injury without receiving additional time.

In 2016, MLB began limiting mound visits -- which previously had no limit -- to 30 seconds starting when the manager or coach has exited the dugout and been granted time by the umpire. As of 2019, clubs are limited to five mound visits per team per nine innings, with teams receiving an additional visit for every extra inning played. Any manager, coach or player visit to the mound counts as a mound visit, though visits to the mound to clean cleats in rainy weather, to check on a potential injury or after the announcement of an offensive substitution are excepted. Normal communication between a player and pitcher that doesn't require either to vacate his position on the field doesn't count as a visit. If a team is out of visits, the umpire will have discretion to grant a brief visit at the catcher's request if a cross-up has occurred between the pitcher and catcher. A rule limiting the number of mound visits to six per nine innings was first established in 2018 before being lowered to five in 2019.

Source: MLB

Painting the Black

A pitcher is said to be "painting the black" when he throws a pitch that barely catches the outside or inside corner of the plate for a strike.

Origin

Home plate is a mostly white slab, but it is bordered on all five sides by a thin black strip. Thus, a pitcher who is frequently hitting the corners of the plate for strikes and avoiding the white portion is said to be painting the black.

Source: MLB

Partner Leagues

The American Association, Frontier League, Atlantic League and Pioneer League are independent baseball leagues that have been designated as Partner Leagues of MLB.

These leagues will collaborate with MLB on initiatives to provide organized baseball to communities throughout the United States and Canada while working to expand the geographic reach of the game.

Previously, the Pioneer League was a Minor League Baseball affiliate. It became an independent league as part of MLB’s reorganization of MiLB in November 2020. The American Association, Frontier League and Atlantic League were already independent before being designated as Partner Leagues.

Meanwhile, five former MiLB affiliated teams -- the Mahoning Valley Scrappers, State College Spikes, Trenton Thunder, West Virginia Black Bears and Williamsport Crosscutters -- have been announced as founding members of the MLB Draft League, which will give eligible prospects a chance to showcase their abilities and gain exposure prior to the MLB Draft. Also, the Appalachian League has been converted from an MiLB affiliate into a collegiate wood-bat summer league.

Source: MLB

Passed Ball (PB)

A catcher is given a passed ball if he cannot hold onto a pitch that -- in the official scorer's judgment -- he should have, and as a result at least one runner moves up on the bases. Passed balls have commonality with wild pitches, as both allow a runner to advance on his own without a stolen base. However, there is a key difference: A passed ball is deemed to be the catcher's fault, while a wild pitch is deemed to be the fault of the pitcher.

A passed ball is not recorded as an error, but when a run scores as the result of a passed ball, it does not count as an earned run against a pitcher. (In cases where this is in question, the official scorer must reconstruct the inning, and if the run would not have scored without the passed ball, that run is deemed unearned.) If a runner advances on a passed ball, he is not credited with a stolen base.

After a strikeout, if the catcher fails to catch the third strike, and the batter reaches first base safely as a result, either a passed ball or a wild pitch must be awarded. In the instance of a wild pitch, that baserunner could count against a pitcher's ERA, but in the instance of a passed ball, he cannot.

Source: MLB

Perceived Velocity (PV)

Perceived Velocity is an attempt to quantify how fast a pitch appears to a hitter, by factoring the Velocity of the pitch and the release point of the pitcher. It takes Velocity one step further -- because a 95 mph fastball will reach a hitter faster if the pitcher releases the ball seven feet in front of the rubber instead of six.

To attain Perceived Velocity, the average Major League "Extension" must first be obtained. Any pitcher who releases the ball from behind the average Extension will have a lower Perceived Velocity than actual Velocity. On the other hand, if a pitcher releases the ball from in front of the average Extension, he'll have a higher Perceived Velocity than actual Velocity.

Perceived Velocity can be a good way to assess pitchers who seem to be sneakily good against hitters. A pitcher throwing a fastball at 93 mph generally shouldn't be blowing hitters away, but if that fastball has a Perceived Velocity of 96, then it makes more sense why hitters might be late on it.

Of course, there is much more to pitching than Velocity and Perceived Velocity. And -- with offspeed pitches especially -- Perceived Velocity isn't always an indicator of a pitcher's success.

As you'd expect, taller pitchers with longer wingspans tend to have higher Perceived Velocities, because their release points tend to be much closer to home plate.

In A Call

"The pitch was clocked at 94 mph but it looked like X mph to the hitter"

Source: MLB

Pickle

A "pickle" is a rundown.

Origin

William Shakespeare is thought to be the first to use the idiom "in a pickle" in The Tempest. But he gave it a somewhat different meaning -- in England, "pickle" actually refers to something close to relish, and one is "in a pickle" if they're inebriated.

But the metaphor got simplified after the phrase came to America. "In a pickle" came to mean "in a tough spot" -- much like a cucumber, stuck sitting in vinegary brine for days on end.

Source: MLB

Pickoff (PK)

A pickoff occurs between pitches when a pitcher throws a ball to a fielder, who eventually puts out or assists in retiring an opposing baserunner. An illegal pickoff attempt results in a balk.

When a pitcher throws to a base between pitches in an attempt to get an out or keep a runner close to the base, it's known as a pickoff attempt. Pickoff attempts are generally used to keep baserunners close to the bag, so they don't get a big lead before attempting to steal a base. Most pickoff attempts do not reach the fielder in time for him to tag out the runner, but certain pitchers possess better pickoff moves than others.

Left-handers, for instance, are generally much better at picking off runners than righties, because most pickoff attempts occur at first base. Lefties are facing first base before they pitch and can simply throw over, while right-handers must step off the pitching rubber and pivot before they throw. However, some right-handers have mastered the art of picking up their foot while spinning toward first.

A team will sometimes use a pickoff move as a stall tactic to get another pitcher in the bullpen warmed up. Or, a team can also use a pickoff move to see if the hitter tips his hand as to whether he intends to bunt.

In A Call

"picked," "nabbed," "caught off the base," "caught napping"

Source: MLB

Pitch Movement

The movement of a pitch is defined in inches, both in raw numbers and (more importantly) as a measurement against average. It is displayed separately for horizontal break and vertical drop.

As opposed to other available pitch movement numbers that remove gravity, Statcast's pitch movement numbers are displayed with gravity, in an attempt to better align with the real-world eye test, as pitches are of course affected by gravity.

Since gravity requires time, and slower pitches aren't "better" just because they have more time to move, the movement of a pitch is compared to "average" movement, by comparing it to other MLB pitch types within +/- 2 MPH and from within +/- 0.5 feet of extension and release.

For example, look at the 2019 curveball drop leaders, minimum 500 thrown. Trevor Bauer got 63.6 inches of drop, while Max Fried got 69.6 inches of drop. However, Bauer got 9.5 inches more drop than average, while Fried got 7.7 inches more drop than average -- because Fried's 74.5 mph curve was nearly 5 mph slower than Bauer's 79.1, giving it more time to drop. Against their comparable averages, Bauer had better drop vs. average.

In A Call

"In 2018, Trevor Bauer's curveball dropped 64 inches. That was 9.3 inches more drop -- or 17% more drop -- than similar MLB curveballs at his velocity, which was the most added drop of any pitcher who threw 200 curves."

Source: MLB

Pitches Per Inning Pitched (P/IP)

Pitches per inning pitched is a tool used to evaluate how efficient a pitcher is at getting his outs -- or how many pitches he typically needs to use to do his job. Calculating the number is easy enough. It's found by dividing a pitcher's total number of pitches thrown by his total number of innings pitched.

Pitchers with the game's best P/IP rate typically average fewer than 15 pitches per inning. A starting pitcher with those numbers would be able to go seven innings on fewer than 105 pitches.

In A Call

"pitches per inning," "pitches per out" (multiplied by three)

Source: MLB

Pitches Per Plate Appearance (P/PA)

P/PA is a simple stat that quantifies how many pitches are thrown per plate appearance. It can be used for both hitters and pitchers, although it is more frequently referred to when assessing hitters.

A player can be a very good hitter if his P/PA is below average, but hitters with high P/PA marks can be useful because they tend to wear out opposing pitchers. If a team has a high P/PA mark, the opposing pitcher will often be forced to exit the game earlier than usual.

Similarly, hitters who see many pitches have a greater likelihood of getting the opposing pitcher make a mistake within the plate appearance.

Source: MLB

Pitches Per Start (P/GS)

Pitches per start tells us how many pitches a starting pitcher throws, on average, in his starts. It can be a useful tool for evaluating pitchers in many ways -- particularly while he's pitching. P/GS gives the viewer an indication of just how much a starting pitcher might have left in the tank.

MLB's leaders in pitches per start are typically veteran pitchers who aren't very injury-prone. Overall skill helps, too, because a manager is obviously more inclined to leave a pitcher in the game longer if he trusts that pitcher to get outs. Young pitchers are generally watched by their clubs, so as to keep their pitch counts down and limit the stress on their arms. The same goes for pitchers who may be prone to arm injuries.

It's important for each team to have at least a couple pitchers with high pitches per start averages, as those pitchers help limit the tax on their teams' bullpens. However, because pitches per start doesn't tell us much about a pitcher's success, it isn't the best way to evaluate how likely a pitcher is to go deep into a ballgame.

In A Call

"pitches per game started," "average pitches as a starter"

Source: MLB

Pitching Coach

Pitching coaches instruct their pitchers on pitching mechanics, pitch selection and preparation while also providing insight into the weaknesses of opposing hitters -- often with the help of video technology.

Pitching coaches can alter a pitcher's arm angle, placement on the pitching rubber or pitch selection in an effort to improve his performance or durability. During a game, the pitching coach assists the manager in making decisions pertaining to the starting pitcher and relief corps. He will also make occasional visits to the mound to help calm down or provide advice to a struggling pitcher.

Source: MLB

Plantar Fasciitis

The plantar fascia is a thick, web-like band of ligament that runs along the sole of the foot, from the bottom of the heel to the base of the toes. It keeps the arch of the foot from flattening completely when the foot is bearing weight, thus providing cushioning and shock absorption. The plantar fascia also allows you to point your toes.

When the plantar fascia becomes inflamed, a baseball player will feel pain in the bottom of the foot, most notably in the heel. Plantar fasciitis, which is the inflammation or thickening of the tissue, is most often caused by repetitive over-stretching of the plantar fascia, which can occur during running.

Typical recovery time

Rest is the best treatment for plantar fasciitis. Surgery may be necessary and involves cutting the ligament to release tension and relieve inflammation. Recovery from surgery is 3-4 months, so some players opt to play through the pain instead, taking days off as needed.

Source: MLB

Plate Appearance (PA)

A plate appearance refers to a batter's turn at the plate. Each completed turn batting is one plate appearance. Plate appearances can often be confused with at-bats. But unlike with at-bats -- which only occur on certain results -- a plate appearance takes into account every single time a batter comes up and a result between batter and pitcher is obtained.

Total plate appearances are used to determine which players have qualified for the batting title; at-bats are not used for this purpose, even though at-bats are used to decipher batting average. This rule is in place because not every plate appearance results in an at-bat, and some hitters -- those who walk and are hit by pitches more frequently -- might not qualify for certain statistical leaderboards if only their at-bats were considered.

The total plate appearances for a team in a game should equal its runs, men left on base and men put out. A batter does not receive a plate appearance if a runner is thrown out on the bases to end the inning while he is at bat, or if the game-winning run scores on a balk, wild pitch or passed ball while he is at bat.

In A Call

"times to the plate," "appearances"

Source: MLB

Plate Appearances Per Strikeout (PA/SO)

Plate appearances per strikeout is a basic ratio determined by dividing a player's total plate appearances by his number of strikeouts. Hitters who don't strike out very much will have high PA/SO marks.

In A Call

"offensive strikeout rate"

Source: MLB

Player Empirical Comparison and Optimization Test Algorithm (PECOTA)

Also a "backronym" for former Major Leaguer Bill Pecota, PECOTA is Baseball Prospectus' system for projecting player performance. The acronym stands for "Player Empirical Comparison and Optimization Test Algorithm." It was developed by Nate Silver in 2003, and Silver ran the projections - which were owned by Baseball Prospectus -- from '03-09, before ceding full responsibility to Baseball Prospectus itself.

PECOTA is perhaps best known for its use of comparable players. In predicting future performance, PECOTA uses historical comparisons of players with similar career paths.

PECOTA is used primarily for projecting the performance of individual players, but it can be applied to entire teams as well to project records. It uses predicted depth charts to establish the projected runs for and against each team, before gleaning a projected win total from that.

Obviously, no one is claiming that every prediction will come true, but PECOTA is widely regarded as one of the most accurate predictors in the industry.

Source: MLB

Player Option

A player option is an optional year at the end of a contract that can be applied at the player's discretion. In such cases, the player has the right to exercise his option and lock in that optional salary as a guaranteed sum or reject the option in favor of testing free agency.

Examples

Following the 2014 season, right-hander Dan Haren exercised a $10 million player option on his contract to remain with the Dodgers (although he was ultimately traded to the Marlins prior to the '15 season). Conversely, Royals outfielder Alex Gordon declined a $14 million player option following the '15 season and tested the free-agent market in search of a larger contract. He went on to re-sign with the Royals on a four-year, $72 million deal.

Source: MLB

Player to Be Named Later (PTBNL)

When clubs consent to include a player to be named later (often abbreviated PTBNL) in a trade, they agree to decide upon or announce the final player involved in that trade at a later date.

Using a PTBNL can be especially advantageous after the non-waiver Trade Deadline, as players that would otherwise be required to first clear waivers can be included in the trade as a PTBNL -- provided they are not on the 25-man roster -- and officially sent to their new club once waiver clearance is no longer mandatory for a trade.

In other instances, the club sending the PTBNL away will provide the acquiring club with a list of players from which to select the PTBNL. In such cases, an agreed-upon deadline -- by which the acquiring club must select the PTBNL -- will often be set.

Example

The July 2007 trade that sent CC Sabathia from the Indians to the Brewers saw Cleveland receive first baseman Matt LaPorta, left-hander Zach Jackson, right-hander Rob Bryson and a PTBNL. The deal was supposed to be centered around LaPorta, but the PTBNL -- Michael Brantley -- has made a far greater big league impact than anyone else the Indians acquired in the transaction.

Source: MLB

Pop Time (POP)

On steal or pickoff attempts by a catcher, Pop Time represents the time elapsed from the moment the pitch hits the catcher's mitt to the moment the intended fielder is projected to receive his throw at the center of the base.

When a throw's flight path ends in front of or beyond the base's midpoint, Statcast accounts for the thrown ball's speed and projects how long the throw would have taken to reach the center of the intended base.

Pop Time is a combination of a catcher's footwork (getting into throwing position), Exchange (glove to release), and Arm Strength (velocity of throw). Pop Time is a much better assessment of a catcher's ability to throw out baserunners than the strength of his arm alone. A catcher with a great arm isn't going to throw out many baserunners if it takes him a while to transfer the ball to his throwing hand and then release the throw.

A catcher with a good Pop Time doesn't always throw out baserunners, however. A large part of his success is dependent upon the runner's speed, the throw's accuracy and the pitcher's delivery length. But with a quick Pop Time and an accurate throw, a catcher is doing what he can to stop the opposing running game.

Below are the best average pop times to second base on stolen-base attempts (min. 15 SB attempts at 2B) from the 2018 season. The MLB average on steal attempts of second base is 2.01 seconds.

1.90 seconds -- J.T. Realmuto
1.93 seconds -- Yan Gomes
1.94 seconds -- Jorge Alfaro
1.94 seconds -- Austin Hedges
1.94 seconds -- Manny Pina
1.94 seconds -- Gary Sanchez

In A Call

"The throw got to the bag in X seconds"

Source: MLB

Pop-up Rate (PO%)

Pop-up rate represents the percentage of balls hit into the field of play that are characterized as pop-ups. Each ball that is hit into the field of play is characterized as a line drive, a fly ball, a ground ball or a pop-up. (A fly ball is a fly to the outfield, while a pop-up is hit to the infield.) Pop-up rate can be used as a metric to evaluate both hitters and pitchers.

Pitchers with high pop-up rates are generally successful because fly balls to the infield almost always result in outs. However, often times a high pop-up rate correlates to a high fly-ball rate, which in turn correlates to a high home-run rate.

Pop-up rates are used far less frequently as an evaluator than line drive, fly-ball and ground-ball rates. In fact, the primary purpose of recording pop-ups is to distinguish them from fly balls.

In A Call

"pop-up percentage"

Source: MLB

Postseason Roster Rules & Eligibility

In a typical season, any player who is on the 40-man roster or 60-day injured list as of 11:59 p.m. ET on Aug. 31 is eligible for the postseason.

Those on the restricted list at that point are also eligible if they haven't been suspended for performance-enhancing drugs during that season. (All players who have served a suspension for PEDs in a given season are ineligible for postseason play that year.)

A player who doesn't meet said criteria for postseason eligibility can still be added to a team's roster in the postseason via petition to the Commissioner's Office if the player was in the organization on Aug. 31 and is replacing someone who is on the injured list and has served the minimum amount of time required for activation. (For example, a player on the 10-day injured list who has been on it for at least 10 days, or a player who has been on the 60-day injured list for at least 60 days.) Players who are acquired in September or after are ineligible.

Postseason roster rules

Teams submit a 26-man roster (it was 25, prior to 2020) prior to each round of the postseason comprised of postseason-eligible players. A club may request permission from the Commissioner's Office to replace a player who is injured during the course of a series, but that player is then ineligible for the rest of that round and the subsequent round, if there is one. A pitcher may be replaced only by another pitcher, and a position player only by another position player.

Teams carry extra players throughout the postseason in the event of injuries, and those players, as well as players on the injured list, can be in the dugout during games, within reason.

Rules for 2020 season

As part of MLB's COVID-19 health and safety protocols during the 2020 season, teams submitted 60-man pools of players eligible to play in 2020. Each club had a 30-man active roster for the first two weeks of the campaign and 28 for the remainder of the season and postseason. Each team was also permitted a three-player taxi squad for every road trip, giving them immediate options to replace an injured or COVID-19 infected player.

Instead of July 31, the Trade Deadline was Aug. 31. Players needed to be on a club's roster by Sept. 15 in order to be eligible for postseason play.

Rather than a 10-day injured list for position players and 15-day injured list for pitchers, there was a 10-day injured list for all players in the shortened season, as well as a separate COVID-19 injured list that had no minimum duration. The 60-day injured list was reduced to 45 days. There were also no restrictions on position players pitching.

Source: MLB

Postseason Share

Each postseason team receives a share of the money earned from playoff gate receipts. The World Series champion receives the highest percentage of the pool, followed by the World Series runner-up, and so on.

The players' pool is formed from 50 percent of the gate receipts from the Wild Card Games; 60 percent of the gate receipts from the first three games of the Division Series; 60 percent of the gate receipts from the first four games of the League Championship Series; and 60 percent of the gate receipts from the first four games of the World Series.

Players from each team vote on how many full or partial shares to award to other club personnel.

Example

The 2019 players' pool amounted to $80,861,145.74. The World Series champion Nationals received $29,110,012.47 of that grand total, while the American League champion Astros received $19,406,674.98. The Nationals voted to award 61 full shares, which amounted to $382,358.18 each. They also issued 14.13 partial shares. The Astros awarded 57 full shares, which amounted to $256,030.16 each, and issued 13.58 partial shares.

Source: MLB

Projected Home Run Distance (HR-DIS)

Projected Home Run Distance represents the distance a home run ball would travel if unhindered by obstructions such as stadium seats or walls. This metric is determined by finding the parabolic arc of the baseball and projecting the remainder of its flight path.

Projected Home Run Distance is a pivotal tool when comparing individual home runs. Looking at Hit Distance alone is not an optimal practice for comparing home runs. This is because each stadium has unique obstructions that prevent balls from completing a full flight path.

Of course, Major League stadiums have different climates, dimensions, wind currents and elevations, which affect the distance batted balls travel. But comparing the distances of monstrous home runs has long been a hobby of baseball fans. And Projected Home Run Distance gives us a slightly fairer way to do that.

In A Call

"projected at X feet," "projected to travel X feet"

Source: MLB

Protested Game

Managers can protest a game when they allege that the umpires have misapplied the rules. The umpires must be notified of the protest at the time the play in question occurs and before the next pitch or attempted play begins. If the play in question ended the game, a protest can be filed with the league office until noon the following day. No protests are permitted on judgment calls by the umpires.

Major League Baseball's executive vice president of baseball operations later determines whether the protested decision violated the rules, though the game will not be replayed unless it is also determined that the violation adversely affected the protesting team's chances of winning.

Source: MLB

Putaway Percentage

Putaway Percentage (PutAway%) is the rate of two-strike pitches that result in a strikeout.

When examined on a pitch-type basis, this can help discern what offering a pitcher uses to finish off hitters, and his effectiveness in doing so. This puts a number to the common baseball phrase of "putaway pitch," providing a more statistically based assessment of the concept.

Example

Highest **PutAway% on sliders**, 2018
Min. 100 two-strike sliders thrown (154 pitchers)

1. Ryan Pressly, 38.8%
2. Edwin Diaz, 37.3%
3. Jose Leclerc, 35.9%
4. Tanner Scott, 35.3%
5. Will Smith, 34.4%

Source: MLB

Putout (PO)

A fielder is credited with a putout when he is the fielder who physically records the act of completing an out -- whether it be by stepping on the base for a forceout, tagging a runner, catching a batted ball, or catching a third strike. A fielder can also receive a putout when he is the fielder deemed by the official scorer to be the closest to a runner called out for interference.

Catchers -- who record putouts by catching pitches that result in strikeouts -- and first basemen -- who record putouts by catching throws on ground-ball outs -- generally amass the highest putout totals.

If a fielder receives a ground ball and steps on a base for a forceout or tags a runner, he is credited with an unassisted putout -- and, obviously, he does not receive credit for an assist. However, if a fielder does so and then throws the ball to another teammate for an out, he is credited with both a putout and an assist.

In A Call

"tagged out" OR "forced out"

Source: MLB

Q

Qualifying Offer

The qualifying offer is a competitive balance measure that was implemented as part of the 2012-16 Collective Bargaining Agreement and restructured under the 2017-21 Collective Bargaining Agreement.

Note: Teams became subject to the following parameters beginning between the 2017 and 2018 seasons.

Clubs wishing to receive compensatory Draft picks for the loss of a free agent can make a one-year "qualifying offer," worth the mean salary of MLB's 125 highest-paid players, to their impending free agents prior to the onset of free agency if and only if:

1. That player has never received a qualifying offer previously in his career.
2. That player spent the entire season on that team's roster (in-season acquisitions are ineligible).

A player will have 10 days to accept or decline the qualifying offer, during which time he can negotiate with other teams to survey his market value. Should a player decide to accept the qualifying offer, he is signed for the following year at that predetermined rate (i.e., the mean salary of the league's 125 highest-paid players). If a player rejects the qualifying offer, he is free to further explore the free-agent market.

MLB Draft compensation

Any team that signs a player who has rejected a qualifying offer is subject to the loss of one or more Draft picks. While a team's highest first-round pick is exempt from forfeiture, any additional first-round picks are eligible. Three tiers of Draft pick forfeiture -- which are based on the financial status of the signing team -- are in place to serve as a penalty for signing a player who rejected a qualifying offer.

(Note: Each pick in the first 10 rounds of the Draft has an assigned value, and the total for each of a club's selections equals what it can spend on signing bonuses for players selected in those rounds without incurring a penalty. When a team forfeits a Draft pick, it also surrenders the accompanying bonus pool money associated that pick, independent from any money forfeited from its international bonus pool per the rules below.)

• A team that exceeded the luxury tax in the preceding season will lose its second- and fifth-highest selections in the following year's Draft as well $1 million from its international bonus pool. If such a team signs multiple qualifying offer free agents, it will forfeit its third- and sixth-highest remaining picks as well. If that team loses a free agent, it will be awarded a Draft pick immediately following the fourth round. The Astros, Cubs and Yankees exceeded the threshold in 2020.

Examples: A team with one pick in each round of the 2021 Rule 4 Draft would lose its second- and fifth-round picks. A team with two first-round picks and one pick in each subsequent round would lose its second-highest first-round pick and its fourth-round pick.

• A team that receives revenue sharing will lose its third-highest selection in the following year's Draft. If it signs two such players, it will also forfeit its fourth-highest remaining pick. If that team loses a free agent, it will be awarded a pick between the first round and Competitive Balance Round A if -- and only if -- the lost player signs for at least $50 million. If the lost player signs for less than $50 million, the team's compensation pick would come after Competitive Balance Round B, which follows the second round.

The following 14 teams qualify for these picks during the 2020-21 offseason: Brewers, D-backs, Indians, Mariners, Marlins, Orioles, Padres, Pirates, Rays, Reds, Rockies, Royals, Tigers and Twins.

Examples: A team with one pick in each round of the 2021 Rule 4 Draft would lose its third-round pick. A team with two first-round picks and one pick in each subsequent round would lose its second-round pick.

• A team that neither exceeded the luxury tax in the preceding season nor receives revenue sharing will lose its second-highest selection in the following year's Draft as well as $500,000 from its international bonus pool. If it signs two such players, it will also forfeit its third-highest remaining pick. If that team loses a free agent, it will be awarded a Draft pick immediately following Competitive Balance Round B. The 13 clubs that fall into this category during the 2020-21 offseason are the Angels, Athletics, Blue Jays, Braves, Cardinals, Dodgers, Giants, Mets, Nationals, Phillies, Rangers, Red Sox and White Sox

Examples: A team with one pick in each round of the 2021 Rule 4 Draft would lose its second-round pick. A team with two first-round picks would lose its second-highest first round-pick.

The Draft-pick compensation is also based on the financial status of the free agent's former team

Like standard Draft picks, compensatory picks in a given tier are ordered in accordance with the previous season's standings. If a team with MLB's worst record and a team with a .500 record both lose a free agent that signs for more than $50 million, the team with the worst record would receive the higher of the two compensatory picks.

Players who are unsigned after the start of the Rule 4 Draft in the year that follows the rejection of their qualifying offer are no longer tied to draft pick compensation and can be signed without their new club needing to forfeit a draft pick.

History of the rule

Under the 2012-16 Collective Bargaining Agreement, players had one week to accept or decline the qualifying offer.

A club that signed a player who rejected a qualifying offer had to surrender its best unprotected pick -- any pick that didn't fall in the top 10 -- in the subsequent Rule 4 Draft. If the club's best pick fell in the top 10, it had to surrender its next-best pick instead. If a club signed more than one player that rejected a qualifying offer, it had to surrender its best and second-best unprotected picks.

Free-agent compensation picks were awarded after the natural first round of the Draft and before Competitive Balance Round A.

Source: MLB

Quality Start (QS)

A starting pitcher records a quality start when he pitches at least six innings and allows three earned runs or fewer. A starting pitcher has two jobs: to prevent runs and get outs. The quality start statistic helps to quantify which pitchers did a "quality" job in those two departments.

Origin:

John Lowe, then a sportswriter for the Philadelphia Inquirer, coined the term in 1985 as a means to gauge whether a pitcher did his job. Lowe also created another wrinkle to go along with the stat. He called quality starts in which a pitcher got the loss "tough losses." And he called non-quality starts in which a pitcher earned the win "cheap wins."

In A Call

"quality outing," "quality performance," "he was quality"

Source: MLB

R

Range Factor (RF)

Range Factor is determined by dividing the sum of a fielder's putouts and assists by his total number of defensive games played.

More recently, Range Factor per nine innings has evolved as the more prevalent statistic because it addresses the discrepancies between a player who plays one inning in a given game and a player who plays the full game.

Of course, circumstances for fielders can vary greatly. With ground-ball pitchers on the mound, for example, an infielder is bound to receive more opportunities to boost his Range Factor. The advent of defensive shifts has affected Range Factor further. For instance, a third baseman who is used frequently in shifts will likely have a higher Range Factor than one who isn't -- even though defensive positioning is generally determined by the manager or bench coach.

Still, Range Factor answers a pivotal question that went long unanswered when fielding percentage was used as the primary evaluative defensive metric: How many plays can a given fielder make? Or, put more simply, how much range does a fielder have?

Origin

Noted sabermetrician Bill James coined Range Factor as a means of assessing a player's defensive capabilities outside the realm of his fielding percentage.

In A Call

"range rating," "range average"

Source: MLB

Reached On Error (ROE)

A batter receives a reached on error when he reaches base because of a defensive error -- meaning he wouldn't have otherwise reached.

Reaching base on an error does not count as a hit, nor does it count as a time on base for purposes of on-base percentage. But there is still significant debate as to whether ROEs are undervalued in the statistical world, as certain players have a tendency to reach base via error more than others.

By definition, errors are primarily the result of a fielder making a mistake. But even with that caveat, certain players -- namely speedy ground-ball hitters -- are likely to record more times reached on error than the average player.

Source: MLB

Regulation Game

A game is considered a regulation game -- also known as an "official game" -- once the visiting team has made 15 outs (five innings) and the home team is leading, or once the home team has made 15 outs regardless of score.

Prior to the 2020 season, if a game was terminated early due to weather before becoming official, the results up to the point of the termination did not count and the game was started over at a later date. But as part of MLB's health and safety protocols during the COVID-19 pandemic, all games cut short due to weather before becoming official were resumed at a later date, rather than started over from scratch, during the 2020 campaign.

The rules below remained in place.

If a regulation game is terminated early due to weather, the results are considered final if the home team is leading. If the home team is trailing, the results are considered final if the game is not in the midst of an inning when the visiting team has taken the lead.

If a regulation game is terminated early due to weather and the game is either tied or in the midst of an inning in which the visiting team has taken the lead, it becomes a suspended game that will be completed at a later date from the point of termination.

If not terminated early, regulation games last until the trailing team has had the chance to make 27 outs (nine innings). If the home team is leading after the visiting team has made three outs in the top of the ninth inning, the home team wins and does not have to come to bat in the bottom of the ninth.

If the game is tied after both teams have made 27 outs each, the game will go to extra innings. It will continue until the home team takes the lead at any point, or the visiting team takes the lead and the home team subsequently makes three outs without tying the game or going ahead.

Source: MLB

Release Waivers

Before a club can formally release a player, that player must first be passed through unconditional release waivers. All 29 other clubs in the Majors have the opportunity to claim the player and add him to their 40-man rosters. A player that is claimed on release waivers has the option of rejecting that claim and instead exploring the free-agent market. Release waivers are often requested after a player's contract is designated for assignment or in cases when a veteran player would otherwise refuse an outright assignment. Players are rarely claimed off release waivers, as the claiming club is required to pick up the remaining contract. Once the player clears waivers, the releasing club is responsible for the old contract.

Example

In April 2013, the White Sox requested release waivers on left-hander Charlie Leesman, and the Rangers opted to claim Leesman. However, Leesman rejected the claim, elected free agency and quickly re-signed a new Minor League contract with the White Sox.

Source: MLB

Relief Pitcher

Relief pitchers stand on the pitching mound, which is located in the center of the infield and 60 feet, six inches away from home plate.

Relief pitchers enter games after the starting pitcher has been removed, usually as a result of poor performance, high pitch count or injury. Many relievers work only an inning or two -- at most -- in a given game, though most clubs have a "long reliever" whose role is to come in to pitch two, three or four innings in relief of a starting pitcher who was removed from a game particularly early. The long reliever can also be useful in extra-inning contests, when the timeframe for a game's conclusion is uncertain.

Relievers typically throw harder than starting pitchers because they can afford to throw at maximum effort, knowing they are unlikely to throw more than 30 pitches in a day. But unlike their starting peers, relief pitchers can be asked to pitch on two or three consecutive days -- sometimes more -- though most relievers will require an off day after pitching three days in a row.

The handedness of a relief pitcher is critical. As a general rule, left-handed batters fare worse against left-handed pitchers, and right-handed batters will sometimes struggle against right-handed pitchers moreso than lefty hurlers. Inversely, a right-handed batter will often excel against left-handed pitchers, and left-handed batters typically perform best against right-handed pitchers.

Left-handed relievers, in particular, are often used in short stints due to their mastery over left-handed batters. Prior to the advent of a three-batter-minimum rule in 2020, it was common for left-handed relievers to enter a game to face just one left-handed opponent before being lifted for a right-handed reliever. Right-handed relievers typically have been used in less specialized fashion, though such matchups are still an important component of managerial decisions.

Source: MLB

Relief Win (RW)

A relief win is defined as any win by a pitcher who was not the starting pitcher. Relievers can earn relief wins in two different ways -- one far more common than the other. First, if a reliever is in the game at the time his team takes the lead for good, he is credited with the victory. A reliever can also pick up the win if the starting pitcher pitches fewer than five innings in what would have been the starter's win, and the official scorer deems that reliever to have been the "most effective" in preserving the win.

Relief victories are inevitably a product of circumstance; they come down to when a pitcher enters the game. Often times, a reliever will allow the tying or go-ahead run to score before his team takes the lead for good in the next half inning. In this case, the reliever didn't do his job very well, but he picks up the win anyway.

In a rarely used clause, an official scorer can deem a relief pitcher's appearance "brief and ineffective." (For example, if a reliever relinquished a one-run lead by allowing three runs, but was still in line for a win after his team scored four runs in the following inning -- that may qualify.) In such cases, the scorer can award the win to a pitcher who followed that "brief and ineffective" pitcher. The pitcher who receives that win is also determined by the official scorer.

In A Call

"wins in relief," "wins out of the bullpen"

Source: MLB

Replay Review

Replay review in Major League Baseball is designed to provide timely review of certain disputed calls and is initiated by a manager challenge or by the umpire crew chief.

All reviews are conducted at the Replay Command Center, which is located at Major League Baseball Advanced Media headquarters in New York, by replay officials -- full-time Major League umpires who work shifts at the Replay Command Center in addition to their on-field shifts. Replay officials review all calls subject to replay review and decide whether to change the call on the field, confirm the call on the field or let stand the call on the field due to the lack of clear and convincing evidence. Beginning in the 2017 season, replay officials are expected to render a decision on a replay review within a two-minute time period (some exceptions permitted).

If replay review results in a change to a call that had been made on the field, the replay official shall exercise his discretion to place both clubs in the position they would have been in had the call on the field been correct.

The decision of the replay official to either uphold or change one or more calls subject to replay review shall be final and is not subject to further review or revision. Once replay review is initiated, on-field personnel from either club who further argue the contested calls or the decision of the replay official shall be ejected. No protest shall ever be permitted on judgment decisions by the replay official.

If a call is overturned on replay review, any decision made by a manager after the play and influenced by the incorrect call shall be nullified. That manager shall be permitted to reaffirm or change his strategic decision based on the result of the play as determined by the replay official.

At any time during a game, a crew chief may initiate a replay review of a potential home run call without a manager challenge being exercised. Beginning in the eighth inning, a crew chief may conduct a replay review of all reviewable calls upon his own initiative or upon the request of a manager who has no remaining manager challenges.

The following calls are reviewable via replay:

Potential home run calls: The umpires' decision to call or not call a home run may be reviewed if there is a question as to whether the ball left the playing field or struck an object; whether the ball struck the top of a fence, hit a railing or otherwise stayed within the field of play; whether the ball was interfered with by a fan reaching over the fence; or whether the ball was fair or foul.
Non-home run boundary calls: Calls involving a decision regarding whether a live ball bounces out of the field of play, strikes the top of a fence or hits a railing or other obstacle in the ballpark, is interfered with by a fan reaching over the fence, is successfully caught by a fielder proximate to a stadium boundary, or leaves the field of play and becomes a dead ball.
Specified fair/foul ball calls: Calls involving a decision regarding whether a batted ball was foul are reviewable only on balls that first land at or beyond the set positions of the first- or third-base umpire.
Force/tag play calls: Calls involving a defensive player's attempt to put out a runner by tagging him or touching a base, and/or whether or not the runner acquired the base.
Catch plays in the outfield: An umpire's decision whether a fielder caught a fly ball or a line drive in flight in the outfield before it hit the ground is reviewable, but fly balls or line drives fielded by a defensive player in the infield is not eligible for review.
Specified baserunning calls: Calls involving whether a baserunner passes a preceding runner, whether a baserunner scored ahead of a third out, and whether a baserunner touched a base.
Hit by pitch: Calls involving whether a pitched ball may have hit a player, a piece of his clothing or his bat. Whether the ball was in the strike zone when it touched the batter and whether the batter made any attempt to avoid being touched by the ball is not be reviewable.
Collisions at home plate: Calls involving a runner deviating from his path to initiate contact with the catcher, and a catcher blocking the path of the runner without being in possession of the ball.
Tag-ups: Whether a runner left the base early or properly touched a base following a catch on a fly ball is reviewable.
Placement of runners: An umpire's placement of a batter and/or runners following any boundary call is reviewable.
Interference on double plays: Calls pertaining to whether a runner intentionally interfered with a fielder in an attempt to break up a double play.

History of the rule

Major League Baseball instituted replay review -- to be used at the umpire's discretion -- on disputed home run calls (fair or foul, in or out of the ballpark, fan interference) on Aug. 28, 2008.

Replay review was expanded starting in the 2014 season, giving managers one challenge to start the game and allowing them to challenge two times in total provided the first challenge resulted in an overturned call. In addition, a much wider range of calls were made subject to review. Clubs could challenge potential home run calls, non-home run boundary calls, tag and force plays (except on a fielder touching second base while turning a double play), fair and foul balls in the outfield, catch plays in the outfield, a potential hit by pitch, whether a runner scored before a third out, whether a runner touched a base, whether a following runner passed the runner ahead of him, and record-keeping situations (ball-strike counts, outs, score and substitutions).

Replay review was modified again in the 2015 season, permitting managers to retain their challenge after every overturned call; allowing them to signal for a challenge during an inning without approaching the umpire on the field; and providing two challenges for any All-Star Game, postseason game and Divisional or Wild Card tiebreaker game. The list of calls that were subject to review was also expanded to include tag-up plays.

The slide rules on attempts to break up a double play were changed in the 2016 season, and calls pertaining to said rule were also made reviewable. Additionally, all force plays were made reviewable in the 2016 season, including a fielder touching second base while turning a double play.

Source: MLB

Retention Bonus (Article XX(B) Free Agents)

If a club signs an Article XX(B) free agent to a Minor League contract between a period after the conclusion of the World Series and 10 days before the start of the next season, it must decide by noon ET five days before Opening Day whether it will add the player to its 26-man roster or MLB injured list at the outset of the season.

If the club does not agree in writing to add the player to its Opening Day 26-man roster or MLB injured list, it must either grant the player his immediate unconditional release or agree to pay the player a retention bonus of $100,000 (to be paid on or before April 15 of the upcoming season).

Players paid the retention bonus can request to be granted their unconditional release on June 1 if they are not added to the 26-man roster or MLB injured list by then. This request must be submitted in writing no later than 2 p.m. ET on May 28.

To qualify for this rule, a player must have at least six years of MLB service time and have finished the previous season on a club's 40-man roster or 60-day injured list.

Example

Brandon Morrow signed a Minor League contract with the Dodgers on Jan. 25, 2017. The right-hander didn't make the club's Opening Day roster, but he was given a $100,000 retention bonus and began the 2017 season with Triple-A Oklahoma City. The Dodgers purchased Morrow's contract from the Minors on May 29, 2017, sent the veteran back down June 10 and recalled him June 21. Morrow then spent the rest of the season with the Dodgers and became a key member of the club's bullpen before signing a two-year MLB deal with the Cubs in December 2017.

Source: MLB

Right Fielder

The right fielder covers the right portion of the outfield grass (when viewing the field from home plate).

Right fielders are not required to have as much speed and range as center fielders. However, they often need to possess the strongest throwing arm in a team's outfield group in order to throw from right field to third base when baserunners attempt to advance from first to third on a hit to right.

 

Source: MLB

Rookie Eligibility

A player shall be considered a rookie unless he has exceeded any of the following thresholds in a previous season (or seasons):

• 130 at-bats or 50 innings pitched in the Major Leagues.
• 45 total days on an active Major League roster prior to Sept. 1, when clubs are allowed to expand their rosters from the 25-player limit to include any player on the 40-man roster.

From Sept. 1 through the end of the regular season, both at-bats and innings pitched count against rookie eligibility but days on a big league roster do not.

A player must have rookie eligibility to be considered for any MLB rookie awards -- such as the American League or National League Rookie of the Year Award -- or appear on any MLB Pipeline prospect lists.

Source: MLB

Rule 4 Draft

The Rule 4 Draft is the official term for the First-Year Player Draft, an amateur draft held annually in early June. Players must be a resident of the United States (U.S. territories, such as Puerto Rico, apply) or Canada to be eligible for the draft. Players who have graduated high school but not attended college are eligible for the draft, as are those who have completed at least one year of junior college. Players attending four-year colleges are eligible to be drafted upon completing their junior year or turning 21 years old.

Each pick in the first 10 rounds of the Draft has an assigned value, and the total for each of a club's selections equals what it can spend on signing bonuses for players selected in those rounds without incurring a penalty.

If a player selected in the first 10 rounds doesn't sign, his pick's value is subtracted from his club's pool. If a team exceeds its allotment, it faces a penalty.

A team that outspends its pool by 0-5 percent pays a 75 percent tax on the overage. At higher thresholds, clubs lose future picks: a first-rounder and a 75 percent tax for surpassing their pool by more than 5 and up to 10 percent; a first- and a second-rounder and a 100 percent tax for more than 10 and up to 15 percent; and two first-rounders and a 100 percent tax for more than 15 percent.

Examples

The Dodgers selected Clayton Kershaw, from Highland Park High School in Texas, with the seventh overall pick in the 2006 Rule 4 Draft. The Nationals selected Stephen Strasburg, a junior out of San Diego State University, with the No. 1 overall pick in 2009. With the first overall selection in 2012, the Astros took Carlos Correa out of the Puerto Rico Baseball Academy.

Source: MLB

Rule 5 Draft

Held each December, the Rule 5 Draft allows clubs without a full 40-man roster to select certain non-40-man roster players from other clubs. Clubs draft in reverse order of the standings from the previous season. Players signed at age 18 or younger need to be added to their club's 40-Man roster within five seasons or they become eligible for the Rule 5 Draft. Players who signed at age 19 or older need to be protected within four seasons.

Not every club will make a selection, but those that do pick a player must pay $100,000 to the club from which said player was selected. Rule 5 Draft picks are assigned directly to the drafting club's 26-man roster and must be placed on outright waivers in order to be removed from the 26-man roster in the subsequent season. Should the player clear waivers, he must be offered back to his previous team for $50,000 and can be outrighted to the Minors only if his original club does not wish to reacquire him. A Rule 5 Draft pick can be placed on the Major League injured list, but he must be active for a minimum of 90 days to avoid being subject to the aforementioned roster restrictions in the next campaign.

Clubs may trade a player selected in the Rule 5 Draft, but the same restrictions apply to the player's new organization. However, a club may also work out a trade with the Rule 5 pick's original club to acquire his full rights, thereby allowing him to be optioned to the Minors under traditional circumstances.

History of the rule

Prior to the 2017-21 Collective Bargaining Agreement, clubs that selected a player in the Rule 5 Draft were required to pay $50,000 to that player's previous team. If the player was placed on outright waivers during the subsequent season and went unclaimed, he would be offered back to his previous team for $25,000.

Read a complete history of the Rule 5 Draft here.

Recent Rule 5 Draft results

2020
2019
2018
2017
2016
2015
2014
2013
2012
2011
2010
2009
2008
2007
2006

Source: MLB

Run (R)

A player is awarded a run if he crosses the plate to score his team a run. When tallying runs scored, the way in which a player reached base is not considered. If a player reaches base by an error or a fielder's choice, as long as he comes around to score, he is still credited with a run. If a player enters the game as a pinch-runner and scores, he is also credited with a run.

The league leaders in runs scored are generally adept at reaching safely and running the bases. But they also tend to score frequently because of favorable positions toward the top their teams' lineups -- a factor that has little to do with the run-scorer's own abilities.

With almost no exception, a pitcher is charged with having allowed a run if a runner he allows to reach base comes around to score. This is different from earned runs, which are not applied if the pitcher allows runs due to defensive errors by his team.

On rare occasions, a pitcher can be charged with a run even when he did not directly allow the scoring player to reach base. If a pitcher allows a baserunner before exiting, and the following pitcher gets a fielder's choice out, the original pitcher is still responsible for the batter who just reached base. This is because the batter who has reached on a fielder's choice is merely replacing the runner put on by the previous pitcher.

In A Call

"runs scored"

Source: MLB

Run Differential

A team's run differential is determined by subtracting the total number of runs (both earned and unearned) it has allowed from the number of runs it has scored.

Example

The 2016 Chicago Cubs scored 808 runs during the regular season and allowed 556 runs, giving them a run differential of +252. The 2018 Baltimore Orioles, meanwhile, scored 622 runs as a team but surrendered 892 runs. Their run differential was -270.

Why it's useful

Examining a team's run differential can help to identify teams that are overachieving and teams that are underachieving. While there have certainly been clubs that have finished a season with a winning record and a negative run differential -- and vice versa -- those teams are statistical outliers. Looking at a team's run differential early in the season can prove instructive when trying to determine whether a club is capable of either sustaining a "hot" start or capable of rebounding from an early slump.

Like any stat, run differential has its limitations and is far from infallible. The team with the best run differential won't always win the World Series. The 2016 Cubs (+252) did just that, but the 2017 Indians (+254) and 2018 Astros (+263) failed to do so. All three clubs won their respective divisions. Generally speaking, the stat is a good barometer for the overall talent of a given team. It is also closely tied to pythagorean winning percentage -- another metric that aims to provide a truer glimpse of a team's talent than raw winning percentage.

Source: MLB

Run Support Per Nine Innings (RS/9)

Run support per nine innings measures how many runs an offense scores for a certain pitcher while that pitcher is in the game. That number is then set over a nine-inning timeframe. So the stat essentially answers the question, "How many runs of support does a pitcher receive per nine innings?"

In no way is RS/9 something a pitcher can control. (On the mound, at least. In National League parks, a pitcher can help his cause as a hitter.) Instead, RS/9 is way of adding context to a pitcher's win-loss record. Does a given pitcher's winning percentage seem a bit too high or a bit too low given his other stats? RS/9 is often the culprit.

It's important to note that for this metric, run support constitutes only the runs that are scored for a pitcher while he is in the game. A few other run-support metrics will take into account how many runs a team scores for its starting pitcher over the course of an entire game. In that vein, RS/9 also works for relief pitchers (although those numbers should be taken with a grain of salt, because relievers have such small sample sizes in terms of innings pitched).

In A Call

"average run support," "support per nine," "runs of support per nine"

Source: MLB

Runs Allowed Per Nine Innings Pitched (RA9)

Runs allowed per nine innings pitched -- the title says it all. It's basically ERA with the "E" removed.

For example, in 1972, Nolan Ryan allowed 80 runs in 284 innings, giving him a 2.54 RA9.

The formula

Runs/IP x 9

Source: MLB

Runs Batted In (RBI)

A batter is credited with an RBI in most cases where the result of his plate appearance is a run being scored. There are a few exceptions, however. A player does not receive an RBI when the run scores as a result of an error or ground into double play.

The most common examples of RBIs are run-scoring hits. However, players also receive an RBI for a bases-loaded walk or hit by pitch. Players can earn RBIs when they make outs, as well, provided the out results in a run or runs (except, as noted above, in the case of double plays).

Along with home runs and batting average, RBIs are a part of baseball's offensive Triple Crown.

In A Call

"ribby," "ribbies," "runs driven in," "runs knocked in," "runs plated," "ribeye"

Source: MLB

Runs Created (RC)

Runs Created estimates a player's offensive contribution in terms of total runs. It combines a player's ability to get on base with his ability to hit for extra bases. Then it divides those two by the player's total opportunities.

For example, in 631 "opportunities" (at-bats + walks), Player A had 377 total bases in 2014, with 66 walks and 195 hits. By this formula -- a very basic version of the formula, which doesn't include baserunning, double plays, etc. -- Player A created 156 runs in the '14 season.

The formula

At its most basic, with as few variables factored in as possible: TB x (H + BB) / (AB + BB)

Why it's useful

Invented by Bill James, Runs Created measures how well a hitter completes one of the central focuses of his job -- creating runs.

Source: MLB

S

Sacrifice Bunt (SH)

A sacrifice bunt occurs when a player is successful in his attempt to advance a runner (or multiple runners) at least one base with a bunt. In this vein, the batter is sacrificing himself (giving up an out) in order to move another runner closer to scoring. When a batter bunts with a runner on third base, it is called a squeeze play and, if successful, is still recorded as a sacrifice.

A sacrifice bunt does not count against a player's batting average or on-base percentage, as the decision to sacrifice often isn't made by the player. Typically, a player will be given a sign by the third-base coach, instructing a bunt attempt. In National League ballparks, pitchers are frequently called upon to sacrifice bunt.

If an error is committed and the batter reaches base, he is still credited with a sacrifice. However, if the sacrifice bunt attempt turns into a single, the batter is simply credited with a hit and no sacrifice is given. An official scorer may determine that a batter was exclusively trying to bunt for a base hit and choose not to give him credit for a sacrifice. However, this is rare in sacrifice situations (with less than two outs and men on base).

In A Call

"sac," "sacrifice," "sac bunt," "gives himself up"

Source: MLB

Sacrifice Fly (SF)

A sacrifice fly occurs when a batter hits a fly-ball out to the outfield or foul territory that allows a runner to score. The batter is given credit for an RBI. (If the ball is dropped for an error but it is determined that the runner would have scored with a catch, then the batter is still credited with a sacrifice fly.)

A sacrifice fly does not count as an at-bat and therefore does not count against a player's batting average. The thinking behind the rule is that with a man on third base and fewer than two outs, a batter will often intentionally try to hit a fly ball, sacrificing his time at bat to help score a run. However, sacrifice flies count against a player's on-base percentage.

Origin

The sacrifice fly was adopted as an official rule in 1954, at which point it was distinguished from the sacrifice bunt. Before 1954, Major League Baseball went back and forth as to whether a sacrifice fly should be counted statistically. In the years that it was counted (1908-31 and '39), it was grouped together with the sacrifice bunt as simply a "sacrifice."

In A Call

"sac fly"

Source: MLB

Salary Arbitration

Players who have three or more years of Major League service but less than six years of Major League service become eligible for salary arbitration if they do not already have a contract for the next season. Players who have less than three but more than two years of service time can also become arbitration eligible if they meet certain criteria; these are known as "Super Two" players. Players and clubs negotiate over salaries, primarily based on comparable players who have signed contracts in recent seasons. A player's salary can indeed be reduced in arbitration -- with 20 percent being the maximum amount by which a salary can be cut.

If the club and player have not agreed on a salary by a deadline in mid-January, the club and player must exchange salary figures for the upcoming season. After the figures are exchanged, a hearing is scheduled in February. If no one-year or multi-year settlement can be reached by the hearing date, the case is brought before a panel of arbitrators. After hearing arguments from both sides, the panel selects either the salary figure of either the player or the club (but not one in between) as the player's salary for the upcoming season.

 

The week prior to the exchange of arbitration figures is when the vast majority of arbitration cases are avoided, either by agreeing to a one- or multi-year contract. Multi-year deals, in these instances, serve as a means to avoid arbitration for each season that is covered under the new contract.

Once a player becomes eligible for salary arbitration, he is eligible each offseason (assuming he is tendered a contract) until he reaches six years of Major League service. At that point, the player becomes eligible for free agency.

Example

Following the 2015 season, Angels outfielder Kole Calhoun had two years and 130 days of Major League service time. That landed Calhoun directly on that offseason's cutoff date for arbitration eligibility, so he was eligible for salary arbitration as a "Super Two" player.

Source: MLB

Save (SV)

A save is awarded to the relief pitcher who finishes a game for the winning team, under certain circumstances. A pitcher cannot receive a save and a win in the same game.

A relief pitcher recording a save must preserve his team's lead while doing one of the following:

  • Enter the game with a lead of no more than three runs and pitch at least one inning.
  • Enter the game with the tying run in the on-deck circle, at the plate or on the bases.
  • Pitch at least three innings.

Origin

The term save was used by general managers in the 1950s, without specific parameters. It simply referred to a pitcher who entered the game with a lead and finished off a win -- regardless of score. Writer Jerome Holtzman was the first to give specific criteria to saves in the early 1960s. But saves didn't become an official stat until 1969.

Source: MLB

Save Opportunity (SVO)

A save opportunity occurs every time a relief pitcher either records a save or a blown save. For a save opportunity, a pitcher must be the final pitcher for his team (and not the winning pitcher) and do one of the following:

Enter the game with a lead of no more than three runs and pitch at least one inning.
Enter the game with the tying run in the on-deck circle -- or closer to scoring.
Pitch at least three innings.
Save opportunities are crucial in determining saves, blown saves and holds. In order for any of those three to occur, a pitcher must first have a save opportunity.

Typically, closers will receive the most save opportunities during the course of a season because their role is to maintain leads at the end of games. A setup man who earns a hold is not credited with a save opportunity, because he neither completed nor blew the save.

Origin

The term save was used by general managers in the 1950s, without specific parameters. It simply referred to a pitcher who entered the game with a lead and finished off a win -- regardless of score. Writer Jerome Holtzman was the first to give specific criteria to saves in the early 1960s. But saves didn't become an official stat until 1969.

Source: MLB

Save Percentage (SV%)

Save percentage represents the percent of time a pitcher records a save when given a save opportunity. Obviously, then, save percentage is calculated by dividing a pitcher's total number of saves by his total number of save opportunities.

Save percentage can be a useful tool for evaluating pitchers who are strictly closers. Ranking pitchers by total saves isn't effective because saves are so reliant on outside factors that a closer can't control -- such as how often a closer's team has a lead in the eighth or ninth innings. But save percentage levels the playing field between closers who get many save opportunities and closers who don't. It simply answers the question: How successful is a closer at getting a save when he has a chance?

If a reliever records a hold, it does not affect his save percentage, because he has not been credited with either a save or a blown save.

Origin

The term save was used by general managers in the 1950s, without specific parameters. It simply referred to a relief pitcher who entered the game with a lead and finished off a win -- regardless of score. Writer Jerome Holtzman was the first to give specific criteria to saves in the early 1960s. But saves didn't become an official stat until 1969.

Source: MLB

Scorekeeping

Different fans have different methods of keeping a scorecard, and many use their own notations. But here's a simple method:

SYMBOLS FOR PLAY
Stat Abbreviation Stat Abbreviation
Single S or - Passed ball PB
Double D or = Stolen base SB
Triple D or = Double play GIDP
Home Run HR or = Error E
Sacrifice SH or SAC Sacrifice fly SF
Walk BB Intentional Walk IBB
Strikeout K Foul fly F
Called out on strikes Forceout FO
Balk BK Line drive L
Fielder's choice FC Bunt
Hit by pitch HP Unassisted U
Wild pitch WP Shortstop 6
Pitcher 1 Left field 7
Catcher 2 Center field 8
First Baseman 3 Right field 9
Second Baseman 4
Third Baseman 5

If the hitter grounds out to shortstop, for example, write in "6-3," which shows the shortstop threw him out at first base. If the hitter flies out to left field, write a "7."

If the batter gets a hit, write in the hit according to which base he reached. Each corner of the box represents a base, with the lower-right corner being first.

If he singles, put a "-" in the lower right. If he doubles, write a "=" in the upper right, and so on. For a walk, use "BB" in the lower right. As the runner advances, mark the appropriate symbol in the appropriate corner.

If a runner scores, put a circle at the bottom of the box, and inside the circle put the symbol of the play and/or the player that drove him in. For example, if the No. 5 hitter drives in two runs with a single, mark his single in the bottom right of his box and mark a circle with the number "5" in it in the boxes of the runners who score (Some people like to use uniform numbers here, so you can tell who did what, even after lineup changes).

At the end of each inning, total the hits and runs for that inning only. At the end of the game you'll be able to add the innings total to get the game score.

Source: MLB

Scouting Grades

Scouting grades have been a staple of MLB.com's prospect coverage for years, and they generally match how clubs grade players as well.

Players are graded on a 20-80 scale: 20-30 is well below average, 40 is below average, 50 is average, 60 is above average and 70-80 is well above average. When discussing prospects, the most important number is the future overall grade, an all-encompassing number on the 20-80 scale that signifies what each player is projected to ultimately be in the big leagues.

A future overall grade of 65 or better is for a player who could develop into a future impact Major Leaguer, perhaps an All-Star-caliber standout. (Note: Some clubs use a 2-8 scale -- as opposed to 20-80 -- which is basically the same thing but without half-grades.)

Source: MLB

Screwball (SC)

A screwball is a breaking ball designed to move in the opposite direction of just about every other breaking pitch. It is one of the rarest pitches thrown in baseball, mostly because of the tax it can put on a pitcher's arm. The movement on the screwball -- which travels toward the pitcher's arm side -- is caused by an extremely unorthodox throwing motion.

Grip

In throwing the screwball, the pitcher snaps his wrist in a manner that causes his palm to face away from his glove side. This is in stark contrast to sliders and curveballs, for which a pitcher snaps his wrist so that the palm is facing the glove side.

Because of the awkward arm motion, a screwball is exponentially tougher to throw than a curveball. But, in theory, it should have the same effect as a curve -- only breaking in the opposite direction.

Origin

The origins of the screwball are very difficult to trace, as it was considered to simply be a different version of a curveball in its early years. Hall of Famer Carl Hubbell, who used the screwball to rejuvenate his career, brought notoriety to the pitch.

In A Call

"scroogie," "reverse curve"

Source: MLB

Second Baseman

The second baseman positions himself between the first- and second-base bags (closer to second base), typically toward the back of the infield dirt.

Second basemen require quick lateral movement to reach balls hit to their right and left. But given that they are stationed on the right side of the infield -- close to first base -- and make shorter throws than shortstops and third basemen, second basemen generally do not need strong throwing arms.

When turning double plays that originate on the left side of the infield, second basemen have a unique challenge in that they must face the shortstop or third baseman to receive the throw. This prevents the second baseman from seeing the oncoming runner while covering the bag. Given this obstacle, second basemen must be able to quickly receive the ball, pivot and -- in some cases -- leap over or sidestep the incoming runner before completing the double-play attempt.

Source: MLB

Seeing-eye Single

A "seeing-eye single" is a softly or moderately struck ground ball that goes between infielders for a base hit.

Origin

Seeing-eye singles are referred to as such because the ball appeared to have seen exactly where it needed to go to avoid the defenders and reach the outfield.

Source: MLB

Service Time

Players receive Major League service time for each day spent on the 26-man roster (it was 25, prior to 2020) or the Major League injured list. Important to players and clubs alike, service time is used to determine when players are eligible for arbitration as well as free agency.

Each Major League regular season consists of 187 days (typically 183 days prior to 2018), and each day spent on the active roster or injured list earns a player one day of service time. Under the 2017-21 Collective Bargaining Agreement, any player who violates the drug program will no longer receive Major League Service during his suspension, unless his suspension is reduced by 20 or more games under the mitigation provision of the program.

A player is deemed to have reached "one year" of Major League service upon accruing 172 days in a given year. Upon reaching six years of Major League service, a player becomes eligible for free agency at the end of that season (unless he has already signed a contract extension that covers one or more of his free-agent seasons).

All players with at least three (but less than six) years of Major League service time become eligible for salary arbitration, through which they can earn substantial raises relative to the Major League minimum salary. Additionally, Major League Baseball each year identifies the group of players that ended the prior season with between two and three years of Major League service and at least 86 days of Major League service in that season and designates the top 22 percent -- in terms of service time -- as arbitration eligible. Those in the top 22 percent -- "Super Two" players -- are also eligible for salary arbitration despite having less than three years of Major League service.

Service time also becomes a factor for players who are considerably further along in their careers. Players with at least 10 years of Major League service who have spent the past five consecutive seasons with the same team earn "10-and-5" rights. Under these circumstances, a player can veto any trade scenario that is proposed. In essence, 10-and-5 rights function as a full no-trade clause.

Source: MLB

Set Position

Pitchers are permitted to use two legal pitching deliveries -- the windup position and the set position -- and either position may be used at any time.

A pitcher is considered to be in the set position when he puts his pivot foot against the pitching rubber, has both shoulders facing first (for lefty pitchers) or third (for righty pitchers) base to some degree and holds the ball with both hands in front of his body. As a result of this configuration, a pitcher in the set position points his glove-hand shoulder toward the batter and his throwing shoulder toward center field. When delivering the ball from the set position, a pitcher simply lifts his free leg up, pushes off the rubber with his pivot foot, strides toward the batter and delivers the pitch to the catcher.

The set position is often used with runners on base, as the length of time needed to complete the delivery is much shorter than the windup position. Thus, pitchers are better able to prevent runners from stealing bases from the set position. To shorten their deliveries further when pitching from the set position, some pitchers use a "slide step" to stride toward the batter rather than first using a full leg kick. Because relievers often enter the game with runners already on base, many pitch from the set position exclusively -- even when the bases are empty.

Source: MLB

Shifts

A shift is a term used to describe the situational defensive realignment of fielders away from their "traditional" starting points. Infield shifts and outfield shifts are tracked separately. In 2017, lefty batters were shifted against on 22.1 percent of their plate appearances, while righty batters saw a shift on 5.2 percent of their plate appearances.

INFIELD POSITIONING

Statcast currently defines infield positioning as one of three categories. More granular categories may be added in the future. A variety of positioning leaderboards are viewable at Baseball Savant.

Standard (Not Shifted)
SHIFT: Three (or more) IF on One Side of 2B
SHIFT: Strategic Positioning

Standard (Not Shifted)

In order to know when a fielder is shifted, you need to know where they're shifting from in the first place. The "standard" alignment is when all four infielders are standing in their traditional spots. (Standard plays are not considered shifts.) Nearly 73 percent of pitches in the 2017 season were with fielders in the "standard" positions.

Standard positions are defined based on the zones where, under neutral conditions (first to eighth inning, no runners on), the league average fielder was positioned 70 percent to 90 percent of the time. For angles below, -45 degrees is the third-base line, 0 degrees is straight up the middle from home plate to center field, and +45 degrees is the first-base line.

Vs. LHH

1B: Between 85-130 feet from home; angle between 31 and 42 degrees
2B: Between 130-160 feet from home; angle between 9 and 31 degrees
SS: Between 130-160 feet from home; angle between -18 and 0 degrees
3B: Between 80-130 feet from home; angle between -37 and -17 degrees

Vs. RHH

1B: Between 85-130 feet from home; angle between 23 and 38 degrees
2B: Between 130-160 feet from home; angle between 0 and 18 degrees
SS: Between 130-160 feet from home; angle between -8 and -28 degrees
3B: Between 80-130 feet from home; angle between -42 and -30 degrees

Three (or more) Infielders on One Side of 2B

Simply put, this is when three (or more, in some cases) infielders are positioned to the same side of second base. This is the most common type of shift.

In 2017, 12.3 percent of tracked pitches came with this shift on, and 11.4 percent of balls in play came against this kind of shift.

Strategic Shift

A "strategic" shift is our current catch-all for positioning that is neither "standard," nor "three infielders to one side of second base." More granular categories, like "guarding the lines," "five infielders," etc., may be added in the future.

Examples of this often include just a single player being out of position, like a second baseman being shifted to short right while no other fielders are, as in the image above, or a shortstop moving very close to the second base bag, outside of the usual shortstop zone, but not quite moving to the other side of it.

Strategic infield shifts happened on 7.5 percent of all pitches in 2017, and were 30.4 percent of all shifts.

This Nick Markakis groundout is a good example of a "strategic" shift. The second baseman and shortstop were both out of their standard positions, but both the shortstop and third baseman remained to the left side of second base.

Video: ARI@ATL: Owings slides for a nice stop up the middle

OUTFIELD POSITIONING

Statcast currently defines outfield positioning as one of three categories. More granular categories may be added in the future.

Standard (Not Shifted)

SHIFT: Three OF on One Side of 2B** SHIFT:** 4th Outfielder** SHIFT:** Strategic Shift

Standard (Not Shifted)

As noted above, in order to know when a fielder is shifted, you need to know where they're shifting from in the first place. The "standard" alignment is when all three outfielders are standing in their traditional spots. (Standard plays are not considered shifts.)

Standard positions are defined based on the zones where, under neutral conditions (first to eighth inning, no runners on), the league average fielder was positioned 70 percent to 90 percent of the time. For angles below, -45 degrees is the third-base line, 0 degrees is straight up the middle from home plate to center field, and +45 degrees is the first-base line.

LF: Between 260-320 feet from home; angle between -33 and -21 degrees
CF: Between 280-350 feet from home; angle between -8 and 7 degrees
RF: Between 260-320 feet from home; angle between 21 and 33 degrees

Three OF on One Side of 2B

Three outfielders to one side of second base is exactly what it sounds like, and it's a relatively rare alignment. In 2017, this was only seen by the D-Backs against Colorado's DJ LeMahieu.

4th Outfielder

"When does an infielder play far enough out to be considered an outfielder" is a complicated question. We are currently considering the line to be "220 feet from home plate." (Read more on that here.) When an infielder gets past that line, we consider him to be a fourth outfielder. This is also a relatively rare alignment, most notably seen by the Cubs against Joey Votto in 2017 and the Astros against Joey Gallo in 2018.

Strategic Shift

As with the infield positioning, an outfield 'strategic' shift occurs when players are in a non-standard alignment that does not fall into another category. In the image shown above, the center fielder is clearly shaded over towards left, outside his traditional spot. Approximately seven percent of pitches in 2017 came with this kind of outfield alignment in place.

Source: MLB

Shortstop

The shortstop positions himself between the third baseman and the second-base bag.

The shortstop is considered the captain of the infield and takes charge on balls hit in the air as well as communication among infielders. If both the shortstop and third baseman are attempting to field the same batted ball, the shortstop will often call off the third baseman.

Shortstops are an integral component of turning double plays. On balls hit to the left side of the infield, a shortstop must cleanly field the ball and accurately throw it to the second baseman covering the second-base bag. On a ball hit to the right side of the infield, the shortstop must cover the second-base bag and receive a throw from either the second baseman or, less frequently, the first baseman and make an accurate relay throw to first. Shortstops will typically cover the second-base bag on grounders hit back to the pitcher in double-play situations, as well.

A good defensive shortstop must possess excellent range, a strong throwing and an ability to field batted balls cleanly. The shortstop position is widely considered the most valuable defensive position in the infield, if not on the entire field of play.

Source: MLB

Shutout (SHO)

A starting pitcher is credited with a shutout when he pitches the entire game for a team and does not allow the opposition to score. By definition, any pitcher who throws a shutout is also awarded a win. Because he recorded every out for his team and didn't allow a run, his team could only have won.

If a starting pitcher does not allow a run but is removed before the game ends, he is not given credit for a shutout. However, if the ensuing reliever(s) also do not allow a run, the team as a whole is credited with a shutout.

In very rare instances, a pitcher can pitch a shutout if he enters in relief. Per official MLB rule 9.18: "No pitcher shall be credited with pitching a shutout unless he pitches the complete game, or unless he enters the game with none out before the opposing team has scored in the first inning, puts out the side without a run scoring and pitches the rest of the game without allowing a run." The latter represents the only circumstance in which a pitcher is credited with a shutout but not a complete game.

In order to complete a shutout, a pitcher must remain in the game for every out. Even if a pitcher throws nine shutout innings, he is not credited with a shutout if the game goes into extra innings. If a game is shortened by rain, a pitcher is still credited with a shutout if he allows no runs and pitches the entire contest.

In A Call

"blanking," "blanked," "held scoreless"

Source: MLB

Single (1B)

A single occurs when a batter hits the ball and reaches first base without the help of an intervening error or attempt to put out another baserunner. Singles are the most common type of hit in baseball, and they occur in many varieties. If a batter beats out a bunt or an infield dribbler -- it's a single. And if a batter hits a rocket to the outfield wall but is held at first base -- it's also a single. (A batter is still credited with a single if he reaches first safely but is thrown out while trying to advance to second.)

The league's leaders in singles are typically speedy contact hitters who bat higher in the batting order. However, the leaderboard for singles isn't as commonly referenced as the leaderboards for home runs, doubles or triples.

Even though the batter only reaches first base, many singles allow runners to advance two bases. A runner is said to be in "scoring position" when he is on second base (or third base), because he could score on a single to the outfield.

In A Call

"base hit," "base knock," "one-bagger"

Source: MLB

Sinker (SI)

The sinker is a pitch with hard downward movement, known for inducing ground balls. It's generally one of the faster pitches thrown and, when effective, induces some of the weakest contact off the bats of opposing hitters.

Sinkerballers -- pitchers who rely on the sinker -- are adept at inducing ground balls and limiting home runs. Such is often possible due to the sinker's sharp downward movement, which is conducive for inducing weak contact.

Origin

According to noted sabermetrician and writer Bill James, while the sinker existed before the 1950s, pitchers didn't explicitly try to throw it. They simply threw their fastballs -- and a select few of them had a sharp sinking movement on them. It is widely believed that around 1950, pitchers began to intentionally incorporate a wide range of movement on their fastballs. That's when the sinker finally came into its own.

In A Call

"sinkerball," "ground-ball pitch," "sinking fastball"

Source: MLB

Skill-interactive Earned Run Average (SIERA)

SIERA quantifies a pitcher's performance by trying to eliminate factors the pitcher can't control by himself. But unlike a stat such as xFIP, SIERA considers balls in play and adjusts for the type of ball in play.

For example, if a pitcher has a high xFIP but has also induced a high proportion of grounders and pop-ups instead of line drives, his SIERA will be lower than his xFIP.

The formula

6.145 - 16.986(SO/PA) + 11.434(BB/PA) - 1.858((GB-FB-PU)/PA) + 7.653((SO/PA)^2) +/- 6.664(((GB-FB-PU)/PA)^2) + 10.130(SO/PA)((GB-FB-PU)/PA) - 5.195(BB/PA)*((GB-FB-PU)/PA)

Source: MLB

Slash Line

Slash line is a colloquial term used to represent a player's batting average, on-base percentage and slugging percentage. Those three stats are often referenced together in baseball media with forward slashes separating them, which is where the term slash line comes from.

A slash line is presented with a player's batting average first, on-base percentage second and slugging percentage third (AVG/OBP/SLG). The latter two stats are added together to generate a player's OPS (on-base plus slugging).

"Slashed" is also sometimes used as a shorthand way to say a player produced a specific slash line, as in "Player A slashed .300/.400/.500 last season."

Source: MLB

Slide Rule

When sliding into a base in an attempt to break up a double play, a runner has to make a "bona fide slide." Such is defined as the runner making contact with the ground before reaching the base, being able to reach the base with a hand or foot, being able to remain on the base at the completion of the slide (except at home plate) and not changing his path for the purpose of initiating contact with a fielder. The slide rule prohibits runners from using a "roll block" or attempting to initiate contact with the fielder by elevating and kicking his leg above the fielder's knee, throwing his arm or his upper body or grabbing the fielder. When a violation of the slide rule occurs, the offending runner and the batter-runner will be called out.

Accidental contact can occur in the course of a permissible slide, and a runner will not be called for interference if contact is caused by a fielder being in the runner's legal pathway to the base.

History of the rule

Amendments to the sliding rules were implemented after a 2015 season in which a number of middle infielders were injured by sliding baserunners while covering second base.

Previously, runners were given a good deal of leeway when sliding into a base in an attempt to break up a double play. Even on plays when they made contact with a fielder, runners were rarely called for interference provided they were in reach of the base at any point in the course of their slides.

Source: MLB

Slider (SL)

A slider is a breaking pitch that is thrown faster and generally with less overall movement than a curveball. It breaks sharply and at a greater velocity than most other breaking pitches. The slider and the curveball are sometimes confused because they generally have the same purpose -- to deceive the hitter with spin and movement away from a pitcher's arm-side. (When a pitch seems to toe the line between the two, it is referred to in slang as a "slurve.")

Most professional pitchers possess either a slider or a curveball -- and some possess both breaking pitches. Having a breaking pitch, like a slider, is an essential component to a professional starter's arsenal, because it keeps the hitter a bit off-balance and unable to commit to gearing up exclusively for a fastball.

A slider is meant to be slightly more deceptive than a curveball because it is thrown harder and has spin that more closely resembles a fastball -- although it doesn't create as much overall movement. Many power relief pitchers possess only a fastball and a slider in their arsenals -- with one pitch setting up the other because of the late deception created by the slider.

Grip

Like a curveball, a slider is thrown by a pitcher with a wrist snap and spin. It is generally perceived as somewhere between a cutter and a curveball. A slider that doesn't break as much as a pitcher hopes is referred to as a "hanging slider" or a "hanger" and is much easier for the batter to hit because of its straight trajectory and sub-fastball velocity.

Origin

When the slider first came to prominence in the first quarter of the 20th century, it was referred to as a "nickel curve." There is no consensus as to who invented the pitch; however, aptly named Hall of Famer Charles Albert "Chief" Bender is widely believed to be the first to bring the pitch to prominence.

In A Call

"snapper," "slide piece," "breaking ball," "sharp breaking ball"

Source: MLB

Slugging Percentage (SLG)

Slugging percentage represents the total number of bases a player records per at-bat. Unlike on-base percentage, slugging percentage deals only with hits and does not include walks and hit-by-pitches in its equation.

Slugging percentage differs from batting average in that all hits are not valued equally. While batting average is calculated by dividing the total number of hits by the total number of at-bats, the formula for slugging percentage is: (1B + 2Bx2 + 3Bx3 + HRx4)/AB.

Although a double is not worth exactly twice as much as a single in the context of scoring runs, slugging percentage is still one of the best evaluators of power, because it accounts for more than just home runs.

Slugging percentage can also be applied as an evaluative tool for pitchers, although this is done less frequently. In such cases, it is referred to as slugging-percentage against.

In A Call

"slugging," as a verb: "to slug"

Source: MLB

Southpaw

A "southpaw" is a left-handed pitcher.

Origin

For decades, the southpaw origin story was a logical one: In the days before lighting systems made night games possible, most ballparks were oriented so that the batter would be looking east out to the mound in order to avoid having to stare into the glare of the afternoon sun. So, with pitchers facing west when they stared into home plate, the arm of a left-handed hurler would be to the south side of the diamond.

However, the earliest mentions of the term in baseball refer to position players, not pitchers. According to MLB official historian John Thorn, baseball has a totally different sport to thank: boxing, in which hitting someone with a left hand came to be known as a punch using the "south paw."

Source: MLB

Spectator Interference

In every case of spectator interference with a batted or thrown ball, the ball shall be declared dead and the baserunners can be placed where the umpire determines they would have been without the interference. When a spectator clearly prevents a fielder from catching a fly ball by reaching onto the field of play, the batter shall be ruled out. But no interference is called if a spectator comes in contact with a batted or thrown ball without reaching onto the field of play -- even if a fielder might have caught the ball had the spectator not been there.

Source: MLB

Spin Rate (SR)

A pitcher's Spin Rate represents the rate of spin on a baseball after it is released. It is measured in revolutions per minute.

The amount of spin on a pitch changes its trajectory. The same pitch thrown at the same Velocity will end up in a different place depending on how much it spins. (For instance, a fastball with a high Spin Rate appears to have a rising effect on the hitter, and it crosses the plate a few inches higher than a fastball of equal Velocity with a lower Spin Rate. Conversely, a lower Spin Rate on a changeup tends to create more movement.)

"The pitch was spinning at a rate of X rpms"

Additional resources

• Spin Rate vs. velocity
• Why Spin Rate matters for fastballs
• How Spin Rate affects curveball outcomes

Source: MLB

Split Contract

A split contract calls for a player to earn different salaries in the Majors Leagues and Minor Leagues. On player on a split contract would earn the pro-rated portion of his Major League salary for any time spent on the Major League roster. That is determined by dividing his Major League salary by 183 (the number of days in the MLB regular season) and multiplying that number by the number of days spent on the Major League roster.

Examples

The Rangers avoided arbitration with catcher Chris Gimenez by agreeing to a one-year split contract with him in December 2015. The deal afforded Gimenez a $975,000 salary upon making the Major League roster.

Source: MLB

Splitter (FS)

A pitcher throws a splitter by gripping the ball with his two fingers "split" on opposite sides of the ball. When thrown with the effort of a fastball, the splitter will drop sharply as it nears home plate.

Splitters are often referred to as "split-finger fastballs," but because of their break and lower velocity, they don't hold much in common with a typical fastball. They're generally thrown in the same situations that would see a pitcher throw his breaking and off-speed pitches. A splitter is generally only slightly faster than a changeup.

Splitters are a relatively uncommon offspeed pitch, but they are still used with some prevalence.

Grip

As mentioned above, a splitter is thrown with a pitcher's two fingers split apart by the baseball. Because of its deceptively slower velocity and sharp drop, a splitter is designed to get the hitter's bat ahead of the pitch and induce weak contact.

Origin

The splitter evolved from the forkball. The two pitches are gripped in almost the same way, except a splitter is generally held with more ease and placed toward the top of the fingers. Splitters are also thrown with the same minimal wrist action as a fastball, unlike the wrist-snap used for a forkball. The splitter received a great deal of recognition thanks to Hall of Fame reliever Bruce Sutter, who threw the pitch with regularity.

In A Call

"split," "split-finger fastball," "split-finger"

Source: MLB

Sprint Speed (SS)

Introduced during the 2017 season, Sprint Speed is a Statcast metric that aims to more precisely quantify speed by measuring how many feet per second a player runs in his fastest one-second window.

In 2018, the metric was updated for hitters/runners to include the top home-to-first times as well as the previously qualified two-base runs, in an attempt to include more useful information and get to a meaningful number more quickly.

Currently, the metric includes "qualified runs" from these two categories:

• Runs of two bases or more on non-homers, excluding runs from second base when an extra-base hit happens.
• Home-to-first runs on "topped" or "weakly hit" balls.

The best of these runs, approximately two-thirds, are averaged for a player's seasonal average.

Any run with a Sprint Speed of at least 30 ft/sec is known as a Bolt.

Why it's useful

Approximately seven full-effort strides can be captured over the course of a one-second window, so Sprint Speed rewards those who can sustain their speed over a longer period of time.

The following leaderboard is the Top 10 of the more than 500 players who had at least 10 qualified runs in the 2018 season.

Top 2018 Sprint Speed by baserunners (min. 10 qualified runs)

30.5 feet per second -- Byron Buxton
30.2 feet per second -- Roman Quinn/Magneuris Sierra
30.1 feet per second -- Adam Engel/Billy Hamilton/Trea Turner
30.0 feet per second -- Delino DeShields/Garrett Hampson
29.9 feet per second -- Harrison Bader/Socrates Brito/Adalberto Mondesi/Isaac Galloway
View full leaderboard

Additional resources

• Statcast introduces Sprint Speed metric
• Sprint Speed updated to track baserunners
• 2018 Sprint Speed update

Source: MLB

Starting Pitcher

Starting pitchers stand on the pitching mound, which is located in the center of the infield and 60 feet, six inches away from home plate.

Starting pitchers, as the position name indicates, are the pitchers that begin each game on the mound for a team. Starters were long asked to pitch as deep into games as possible, although many clubs in modern baseball employ pitch counts and will not let starting pitchers throw many more than 100 pitches in a start. This is done in an effort to preserve pitchers' health.

Starting pitchers do not field many batted balls, but they are often expected to make plays on weak grounders and bunted balls back to the mound. Beyond that, other infielders will typically call off a pitcher in pursuit of a ball in play. Even popups hit above or near the pitching mound will usually be fielded by an infielder who calls off the pitcher.

Teams in today's game typically rotate between five starting pitchers, meaning starters usually have four to five days off between trips to the mound.

Starting pitchers hit regularly in the National League only, as the American League utilizes a designated hitter in place of the pitcher.

Source: MLB

Steamer

Steamer is a system of projections developed by Jared Cross -- a high school science teacher in Brooklyn -- and two of his former students, Dash Davidson and Peter Rosenbloom. It is currently used by Fangraphs as its primary projection system for individual players.

According to Steamer's website, the projection system got its name because St. Ann's High School goes by the nickname the "Steamers." The system began simply as part of an independent research program at the high school, on which Davidson and Rosenbloom teamed up with Cross.

Like other projection systems, Steamer uses past performance and aging trends to develop a future projection for players. It also uses pitch-tracking data to help forecast pitchers. On Fangraphs, the projections are updated daily and predict each player's numbers over the course of the remainder of the season.

Obviously, no one is claiming that every one of Steamer's predictions will come true, but it is widely regarded as one of the most accurate predictors in the industry.

Source: MLB

Stolen Base (SB)

A stolen base occurs when a baserunner advances by taking a base to which he isn't entitled. This generally occurs when a pitcher is throwing a pitch, but it can also occur while the pitcher still has the ball or is attempting a pickoff, or as the catcher is throwing the ball back to the pitcher.

A stolen base is not automatically credited when a runner advances during one of the aforementioned scenarios; the official scorer must also determine that the runner had been in attempt of a steal. For example, if a runner takes an extra base on a wild pitch or a passed ball, he is not awarded a stolen base. However, if he was attempting to steal as a wild pitch/passed ball was thrown, he is generally given credit for it.

A baserunner is not given credit for a steal if he takes the extra base as the result of an error by the opposing defense. He is not given credit for a steal if he safely advances but another runner also attempting to steal on the same play is thrown out. (This maneuver is called a "double steal.") He is also not given credit if the defense concedes the base because of the situation in the game. (This generally occurs very late in the contest, with the defensive team ahead by more than one run. The defense -- not wanting to play out of position -- doesn't cover the base and, as a result, the ruling is "defensive indifference" rather than a stolen base.)

Stolen bases have long been an integral part -- and one of the most debated aspects -- of the game. The upside to a stolen base is obvious; the runner advances a base and puts himself closer to scoring. However, the downside -- a baserunner making an out -- arguably far outweighs the upside. In this vein, a runner who steals bases at a 50 percent clip is considered to be doing his team a disservice. As a general rule of thumb, a base stealer with a stolen-base percentage of 75 or higher is helping his team by attempting steals.

There are few maneuvers in baseball more strategic than a stolen-base attempt. In some cases, the third-base coach will give the runner a sign, telling him to steal. But certain runners, who have proven to be competent base stealers, are given "the green light," whereby they can take off at their discretion. One of the most common times to steal occurs with two outs and the hitter behind in the count. In this case, the downside to stealing is minimized. If the runner is thrown out, the hitter gets a fresh count to start the next inning. But if the runner is safe, he has put himself in scoring position.

The league leaders in stolen bases are almost always among the fastest players in the league, for obvious reasons. However, speed is only one ingredient in the stolen base. A base stealer must also be adept at choosing a good pitch to run on (generally a breaking ball, which will travel slower to the plate than a fastball and sometimes bounce in the dirt). He must also be able to read the situation and a pitcher's pickoff move to get a good first step.

Origin

The modern steal rule was put into place in 1898. Before then, any time a runner took an extra base (such as advancing to third base from first on a single) he was awarded a stolen base.

In A Call

"swipes," "steals," "stolen bags"

Source: MLB

Stolen-base Percentage (SB%)

Stolen-base percentage is determined by the number of steals for a player divided by his total number of attempts. SB% is an essential tool in evaluating base stealers, because the league leaders in stolen bases often get thrown out frequently, too. In that vein, stolen bases are useful -- but only if a base stealer isn't at a high risk of getting thrown out.

Because a caught stealing is much more harmful than a stolen base is helpful, there is plenty of debate in baseball circles as to when it's worth attempting a steal. As a general rule of thumb, a base stealer with an SB% of 75 or higher is typically helping his team by attempting to steal.

Often times, players without great speed or a high number of steals can post high stolen-base percentages. This comes from an understanding of the situation and when it might be a good time to take the risk.

Fantasy advantage

A player with a low stolen-base percentage may be inclined -- or asked by his team -- to attempt fewer steals, thus hurting his fantasy value. Conversely, a player with a high stolen-base percentage -- provided he is active on the bases -- will likely have more latitude to steal in the future.

In A Call

"stealing percentage," "steal percentage"

Source: MLB

Strike Zone

The official strike zone is the area over home plate from the midpoint between a batter's shoulders and the top of the uniform pants -- when the batter is in his stance and prepared to swing at a pitched ball -- and a point just below the kneecap. In order to get a strike call, part of the ball must cross over part of home plate while in the aforementioned area.

Strikes and balls are called by the home-plate umpire after every pitch has passed the batter, unless the batter makes contact with the baseball (in which case the pitch is automatically a strike).

History of the rule

The vertical specifications of the strike zone have been altered several times during the history of baseball, with the current version being implemented in 1996.

Past strike zones

From 1988-95, the strike zone went from the midpoint between the shoulders and the top of the uniform pants, to the top of the knees.
From 1969-87, the strike zone went from the batter's armpits to the top of the knees. This strike zone was implemented, along with the lowering of the mound from 15 inches to 10 inches, in response to a 1968 season -- now known as the "Year of the Pitcher" -- in which the dominance of hurlers reached new heights.
From 1963-68, the strike zone went from the top of the batter's shoulders to the knees.
From 1950-62, the strike zone went from the batter's armpits to the top of the knees.
The version of the strike zone used from 1963-68 was also utilized prior to 1950, going back to the late 1800s.

Note: The box outlined above delineates the borders of the Major League strike zone.

Source: MLB

Strikeout (SO, K)

A strikeout occurs when a pitcher throws any combination of three swinging or looking strikes to a hitter. (A foul ball counts as a strike, but it cannot be the third and final strike of the at-bat. A foul tip, which is caught by the catcher, is considered a third strike.)

The batter is automatically out on a strikeout, unless the catcher does not cleanly hold onto the baseball or if the baseball hits the dirt. If the catcher does not catch the third strike, the batter may attempt to run to first base -- if it is open or if there are two outs. However, even if the batter reaches first base safely, the pitcher and the batter are still credited with a strikeout in the scorebook.

In the scorebook, a strikeout is denoted by the letter K. A third-strike call on which the batter doesn't swing is denoted with a backward K.

Origin

Before 1858, the strikeout required three pitches be offered at and missed. However, in 1858, the addition of the called strike was implemented and the strikeout rule has changed very little since.

In A Call

"whiff," "K," "punch out" (for pitchers); as a verb in place of "strikes out": "fans," "rings up," "whiffs," "K's," "punches out"

Source: MLB

Strikeout-to-walk Ratio (K/BB)

K/BB ratio tells us how many strikeouts a pitcher records for each walk he allows. The number is found simply by dividing a pitcher's total number of strikeouts by his total number of walks. It's an essential tool for evaluating pitchers.

In A Call

"K's per walk," "strikeouts per walk," "strikeout-to-walk ratio," "strikeouts vs. walks ratio"

Source: MLB

Strikeouts Per Nine Innings (K/9)

K/9 rate measures how many strikeouts a pitcher averages for every nine innings pitched. It is determined by dividing his strikeout total by his innings pitched total and multiplying the result by nine.

Because a strikeout is so straightforward -- with no chance of error or bad luck, like on a ball in play -- a pitcher's K/9 rate reveals a lot about his success. However, there are many successful pitchers who get by with lower K/9 rates by inducing a high rate of ground balls and/or soft contact.

K/9 rate tells us a lot, but it's important to note the difference between starters and relievers within the statistic. Because relievers generally pitch for such a short period of time and aren't as concerned about conserving pitches, they can throw with higher intensity for each batter. As a result, relief-pitcher K/9 numbers are generally higher than those of starting pitchers.

In A Call

"K's per nine," "K-rate per nine," "strikeout rate per nine"

Source: MLB

Substitutions

Teams are permitted to substitute players any time the ball is dead. The manager must immediately notify the umpire of the switch and substitutes must bat in the replaced player's batting-order position. Once removed, players are not permitted to return to the game in any capacity. Types of substitutions include pinch-hitting, pinch-running, a pitching change and a defensive replacement.

Barring injury or illness, the starting pitcher must pitch until at least one batter reaches base or is put out. Any substitute pitcher must pitch until at least one batter reaches base or is put out, or the offensive team is put out in some other manner.

A double-switch refers to the act of substituting two players at once. The tactic is typically used in the National League to bring in a new pitcher when the pitcher's spot in the batting order is due up in the next half-inning. Rather than performing a straight one-for-one swap of pitcher for pitcher, a team subs the new pitcher into the batting-order spot of a non-pitcher and subs another non-pitcher into the removed pitcher's batting-order spot. That way, the team can avoid having the pitcher come to bat in the next half-inning without needing to use additional substitutions for a pinch-hitter and then another pitcher.

Impending rule changes that will go into effect at the start of the 2020 season

In an effort to reduce the number of pitching changes and, in turn, cut down the average time per game, MLB will institute a rule change beginning in 2020 that requires pitchers to either face a minimum of three batters in an appearance or pitch to the end of a half-inning, with exceptions for injuries and illnesses.

Source: MLB

Super Two

Players typically must accrue three years of Major League service time -- with one year of service time equaling 172 days on the 25-man roster or the Major League injured list -- to become eligible for salary arbitration. Super Two is a designation that allows a select group of players to become eligible for arbitration before reaching three years of service time.

To qualify for the Super Two designation, players must rank in the top 22 percent, in terms of service time, among those who have amassed between two and three years in the Majors. Typically, this applies to players who have two years and at least 130 days of service time, although the specific cutoff date varies on a year-to-year basis.

Example

Dexter Fowler completed the 2011 season with two years and 168 days of Major League service time, which made him one of the leaders in service time among players who had between two and three years in the Majors. Thus, the outfielder qualified as a Super Two player and was eligible for arbitration. Fowler went through arbitration four times before reaching free agency following the 2015 season.

Source: MLB

Suspended Game

A suspended game is a game that is stopped early and must be completed at a later date from the point of termination, though not all terminated games become suspended games.

The most frequent cause of a suspended game is when a regulation game is terminated due to weather, and the game is either tied or in the midst of an inning in which the visiting team has taken the lead. Other rarer causes for suspended games include a technical malfunction in the stadium that prevents the game from continuing.

Prior to the 2020 season, if a regular season game was terminated early before becoming official, the results up to the point of the termination did not count and the game was started over at a later date. But as part of MLB's health and safety protocols during the COVID-19 pandemic, all games cut short before becoming official were resumed at a later date, rather than started over from scratch, during the 2020 campaign. This matched the rules that have been in place since 2008 for all postseason games and any tiebreaker games added to the end of the regular season.

Source: MLB

Sweet Spot

Colloquially, a player who hits the ball solidly is said to have gotten the "sweet spot" of the bat on the ball. The sweet spot classification quantifies that as a batted-ball event with a launch angle ranging from 8 to 32 degrees.

A player's sweet spot percentage -- or how often he produces a batted-ball event in the launch angle sweet-spot zone of 8-32 degrees -- is presented on Statcast leaderboards under SwSp%.

Why it's useful

Sweet spot percentage can be used in concert with hard-hit rate -- the percentage of a player's batted balls that have an exit velocity of 95 mph or higher. For a batted-ball classification that takes into account both launch angle and exit velocity, check out barrels.

Source: MLB

T

TOOTBLAN

TOOTBLAN is an acronym that stands for Thrown Out on the Bases Like a Nincompoop.

Essentially, the TOOTBLAN describes any non-force out a player makes on the bases, including outs made while attempting to take an extra base, outs on would-be sacrifice flies, pickoffs, double-offs, fielder’s choice outs with an open base, batter and runner interference and getting hit by a batted ball.

Coined by Cubs blogger Tony Jewell in 2008, the TOOTBLAN was invented to measure the impact poor baserunning has on a player’s on-base percentage and offensive value.

Jewell initially invented the TOOTBLAN as part of what he called the Ryan Theriot Adjusted On-Base Percentage, which was created to examine Theriot’s true value to the 2008 Cubs. The RTAOBP was an equation that subtracted caught stealings and TOOTBLANs from Theriot’s actual OBP, which was .387 in 2008.

Source: MLB

Texas Leaguer

A "Texas Leaguer" is a bloop that falls between an outfielder and an infielder for a hit.

Origin

Texas Leaguer dates back to 1901, when a rookie named Ollie Pickering made his debut for the Cleveland Blues (the franchise that would later become the Indians). Pickering had become a legend as a Minor Leaguer in the Texas League, and he was immediately placed atop Cleveland's lineup when he was called up -- he even holds the honor of taking the first at-bat in the history of the American League.

Pickering proceeded to have one of the most fortunate starts to his career imaginable, as his first seven plate appearances all resulted in bloop singles. His teammates decided to name the play after him, and it's stuck ever since.

Source: MLB

The Hot Stove

"The Hot Stove" refers to the Major League Baseball offseason, particularly the time around the Winter Meetings when free-agent signings and trades are most prevalent.

Origin

In the early days of baseball, Hot Stove Season referred to an actual baseball season: Hot Stove Leagues, in which MLB players would stay in shape by playing baseball in their hometowns while staying warm with actual hot stoves.

The term soon expanded to become a kind of predecessor to the water cooler -- on a cold day, fans would gather around the hot stove to discuss their favorite team.

Source: MLB

Third Baseman

The third baseman positions himself in the vicinity of the third-base bag, facing home plate with the base in front of him and to the right.

On defense: Third basemen are responsible for fielding ground balls, line drives and pop flies in the general vicinity of the third-base bag. They ideally possess strong, accurate arms with which to throw across the diamond and quick reaction times given their close proximity to home plate. Notably, third basemen must also be prepared to field bunt attempts, as batters will often bunt the ball down the third-base line in sacrifice situations or in an attempt to record a "bunt base hit" in surprise fashion.

Third basemen typically have less ground to cover than the shortstop playing beside them and therefore tend to possess less lateral range.

 

Source: MLB

Third-base Coach

The third-base coach stands in foul ground, just behind the third-base bag, and helps relay signals from the dugout to both batters and baserunners. With a batter at the plate, a third-base coach will use pre-determined hand and arm gestures to indicate when said batter is expected to bunt, execute a "hit-and-run," or "take a pitch." By rule, the third-base coach must stay within the designated coach's box on the third-base side of home plate prior to each pitch. The coach may leave said box to signal a player once a ball is in play, provided the coach does not interfere with the play.

Additionally, the third-base coach is responsible for advising baserunners on whether to stop at second and third base or to continue running home. He must know the speed of each runner, the location of the batted ball and the arm strength and accuracy of a fielder who is in the process of fielding the ball. Third-base coaches must act decisively and do so in the blink of an eye, as they often have just a second or two to decide whether to send a runner past third base in an attempt to score.

Source: MLB

Thoracic Outlet Syndrome

The thoracic outlet lies at the lower part of the neck, beginning just above and behind the collarbone and extending into the upper arm and chest. Thoracic Outlet Syndrome results when the nerves and blood vessels in this area are compressed, resulting in pain, weakness, fatigue and numbness or tingling in the arm or hand, particularly with activities in which the arm is elevated.

During surgery to correct Thoracic Outlet Syndrome, both the first rib -- the uppermost of the ribs, which is attached to the first thoracic vertebrae at the base of the neck, angles down and connects to the sternum just below the collarbone -- and the scalene muscles are removed to clear space for the nerves in the thoracic outlet.

Typical recovery time

Not many pitchers have undergone Thoracic Outlet Syndrome surgery, so the recovery timeline is still inexact. But even in a best case scenario, a pitcher is unlikely to be ready to return until at least 12 weeks after the procedure.

Source: MLB

Three True Outcomes

The "three true outcomes" in baseball are said to be a home run, a walk or a strikeout due to the fact that none of the three, with the rare exception of an inside-the-park home run or a strikeout with a dropped third strike, involve the defense beyond the pitcher or the catcher. The phrase, which was coined by baseball writer and historian Christina Kahrl, can also be used as an adjective, calling someone a "three-true-outcomes player." Players with well above-average power, walk rates and strikeout tendencies often bear that description.

Examples

Modern-day examples of this type of player include Joey Gallo and Miguel Sano, while Adam Dunn is among the more famed three-true-outcomes players in recent history. Dunn either walked, homered or struck out in 49.9 percent of his 8,328 Major League plate appearances.

Source: MLB

Three-batter Minimum

In an effort to reduce the number of pitching changes and, in turn, cut down the average time per game, MLB instituted a rule change that requires pitchers to either face a minimum of three batters in an appearance or pitch to the end of a half-inning, with exceptions for injuries and illnesses. If a pitcher faces one batter to end an inning, he may be removed, but if he is brought back for a second inning, he must still face two more batters for a total of three.

Previously, Rule 5.10(f) stated that the starting pitcher must pitch to one batter until that batter was put out or reached base, and Rule 5.10(g) stated that any reliever must pitch to one batter until that batter was put out or reached base, or the offensive team was put out, with exceptions for injuries and illnesses. These rules were in effect through the end of the 2019 season.

Source: MLB

Tommy John Surgery

Tommy John surgery is a procedure in which a partial or fully torn ulnar collateral ligament on the medial side of the elbow is replaced with a tendon from another part of a patient's body or from a cadaver.

The procedure was first performed by Dr. Frank Jobe on Dodgers pitcher Tommy John in September 1974. Taking a tendon from John's wrist, Jobe drilled holes into John's ulna and humerus bones and grafted the tendon in a basic figure-eight design, held in place by anchors. Jobe said in 2013 that he gave the procedure "about a one in 100 chance" of working at the time. John returned to big league action in April 1976.

The second Tommy John surgery wasn't done until 1978, when pitcher Brent Strom was operated on by Jobe. Tommy John surgery has become much more common in the years since then. The procedure has revolutionized the game, making it possible and even probable to return from an injury that previously was likely to end a career. As of June 2017, 86 percent of all players who had reportedly undergone Tommy John surgery had at the very least returned to the competition level they were at prior to the procedure. For example, a Triple-A pitcher who had Tommy John surgery and subsequently made it back to Triple-A or appeared in the Majors would count toward the 86 percent of successful cases.

Typical recovery time

Pitchers who have undergone Tommy John surgery are usually given a recovery timetable of 12 to 18 months. The recovery time is much less certain for those undergoing the procedure for a second time, though fewer than 90 players are known to have had the surgery more than once, as of August 2017.

A experimental procedure known as "primary repair" has emerged as a potential alternative to Tommy John surgery, offering a shorter recovery time. The procedure uses a technique, pioneered by Dr. Gordon Mackay, in which a product called SutureTape is attached to two screws inserted into the bones at each end of a ligament or tendon, providing a framework against which the ligament or tendon can heal. Because the SutureTape is porous, the damaged ligament or tendon grows through the lattice of the SutureTape and is supported by it.

Source: MLB

Tools of Ignorance

"Tools of ignorance" is a nickname for the catcher's equipment.

Origin

Coined by catcher Herold "Muddy" Ruel, who played from 1915 through 1934, the term is meant to point out the irony that a player with the intelligence needed to be effective behind the plate would be foolish enough to play a position that required so much safety equipment.

Source: MLB

Total Bases (TB)

Total bases refer to the number of bases gained by a batter through his hits. A batter records one total base for a single, two total bases for a double, three total bases for a triple and four total bases for a home run.

Total bases are used to determine a player's slugging percentage -- which is total bases divided by at-bats. A player can only add to his total-bases tally through a hit. Advancing on the basepaths -- even via a steal -- has no impact on a player's total bases.

In A Call

"total bags"

Source: MLB

Total Chances (TC)

In theory, a defender's total chances represent the number of opportunities he has to record an out. The formula for total chances is: assists plus putouts plus errors.

The use of the statistic is almost exclusively limited to its role as the denominator for determining fielding percentage. The biggest flaw with total chances is that it doesn't account for difficult defensive plays that get made. For instance, a diving catch that is made by a defender counts as a "chance," but if that same play falls in for a hit, it doesn't count as a "chance" for that defender.

In A Call

"defensive chances," "chances"

Source: MLB

Trade Deadline

In a typical season, the Trade Deadline almost always* falls at 4 p.m. ET on July 31 and is the last point during the regular season at which players can be traded from one club to another.

* Major League Baseball set the 2016 Trade Deadline for Monday, Aug. 1., in order to avoid having the deadline fall in the middle of the schedule of day games on Sunday, July 31. Pushing the deadline back one day to Aug. 1 -- when no games were scheduled to begin before 7 p.m. ET -- prevented players from being traded in the midst of active games.

Note: After the COVID-19 pandemic delayed the 2020 regular season, the '20 Trade Deadline was Aug. 31. Players needed to be on a club's roster by Sept. 15 in order to be eligible for postseason play.

2019 rule change

Prior to 2019, July 31 was referred to as the non-waiver Trade Deadline, and players could be traded after that date if they first cleared revocable trade waivers.

The player's original club had three options when a waiver claim was placed: It could either work out a standard trade with the claiming club (the two sides had 48 hours to agree to a deal), allow the player -- and all money remaining on his contract -- to go to the claiming club with no return or pull the player back off waivers. A player who was pulled back off waivers could be placed on trade waivers a second time, but at that point the waiver request became irrevocable. If a player passed through waivers unclaimed, he could then be traded to any club, free of restriction (though all 40-man-roster players in the trade had to clear waivers before being dealt).

Although trades could be completed after Aug. 31 under the old rules, the last day in August was sometimes colloquially referred to as the "waiver Trade Deadline," as players acquired after that date were ineligible to be added to the postseason roster by their new teams.

As of 2019, the July 31 Trade Deadline is the only trade deadline. Players may still be placed and claimed on outright waivers after July 31, but trades will no longer be permitted after that date. With regards to newly acquired players, the Aug. 31 postseason roster deadline remains in effect.

Source: MLB

Trade Waivers & Aug. 31 'Deadline'

In a typical season, the Trade Deadline almost always falls on July 31. Players may still be placed and claimed on outright waivers after July 31, but trades aren't permitted after that date.

Note: After the COVID-19 pandemic delayed the 2020 regular season, the '20 Trade Deadline was Aug. 31. Players needed to be on a club's roster by Sept. 15 in order to be eligible for postseason play.

Prior to 2019, players could still be traded following the July 31 Trade Deadline if they first cleared revocable trade waivers. Although trades could be completed after Aug. 31 under the old rules, the last day in August was sometimes colloquially referred to as the "waiver Trade Deadline," as players acquired after that date were ineligible to be added to the postseason roster by their new teams. With regards to newly acquired players, the Aug. 31 postseason roster deadline remains in effect during a typical season.

Under the old system, the player's original club had three options when a waiver claim was placed: It could either work out a standard trade with the claiming club (the two sides had 48 hours to agree to a deal), allow the player -- and all money remaining on his contract -- to go to the claiming club with no return or pull the player back off waivers. A player who was pulled back off waivers could be placed on trade waivers a second time, but at that point the waiver request became irrevocable. If a player passed through waivers unclaimed, he could then be traded to any club, free of restriction (though all 40-man-roster players in the trade had to clear waivers before being dealt).

Examples of Trade Waivers

The Chicago Cubs claimed Cole Hamels from the Philadelphia Phillies in August 2014, but the two sides weren't able to work out a trade in the allotted 48 hours and Hamels was pulled back by the Phillies.

The White Sox claimed Alex Rios off waivers from the Blue Jays in August 2009, and Toronto elected to allow Rios to go to the White Sox without compensation as a means of shedding the nearly $60 million remaining on his contract.

In August 2013, the Pittsburgh Pirates claimed Justin Morneau off waivers from the Minnesota Twins, and the two sides agreed to a trade that sent Morneau to Pittsburgh in exchange for outfielder Alex Presley and a player to be named later.

Justin Verlander was sent from the Tigers to the Astros for a trio of Minor Leaguers shortly before midnight on Aug. 31, 2017. Verlander had cleared revocable trade waivers earlier in the month, making him eligible to be dealt to any team.

Source: MLB

Triple (3B)

Often called "the most exciting play in baseball," a triple occurs when a batter hits the ball into play and reaches third base without the help of an intervening error or attempt to put out another baserunner.

Triples are almost exclusively hit by faster players because Major League defenses are usually able to get the ball back to the infield before a slower runner can attempt to take third base. Also, triples are more likely to occur on balls hit to the right side of the field, because the throw from right field to third base is tougher than the throw coming from left field to third.

Because of the nature of a triple -- with the batter covering three bases, or 270 feet -- there is almost always a close play at third base. Stand-up triples are very rare.

In A Call

"three-bagger," "three-base hit," "extra bases," "the most exciting play in baseball"

Source: MLB

Triple Play (TP)

A triple play occurs when the defending team records three outs on a single defensive play.

Triple plays are rare for several reasons. First off, they can occur only when the batting team has at least two men on base with nobody out. Then, in those cases, the batting team typically has to make a baserunning blunder to aid the defending team. The most common form of a triple play begins with a hard line drive at an infielder. In this instance, runners sometimes have already left their bases -- either to steal, as part of a hit and run or simply because they didn't get a good read on where the ball was headed. The defense will then throw to both bases, getting both runners out.

Still, there is no common method for a triple play, like there is with a ground-ball double play. There have been ground-ball triple plays, typically with a slow runner batting. There have also been situations where multiple runners get caught in rundowns. Additionally, triple plays have resulted from confusion at an umpire's call.

One of the rarest occurrences in baseball is the unassisted triple play, where a single fielder turns a triple play without ever giving up the baseball. There are no defensive assists on the play, and thus it is unassisted. Every unassisted triple play in history (through the 2016 season) has followed a pattern, where the three outs are recorded by: 1. An infielder catching a line drive, and 2. that infielder tagging a runner and stepping on second base (in no particular order).

In A Call

"turn three"

Source: MLB

Two-Seam Fastball (FT)

A two-seam fastball is generally one of a pitcher's fastest pitches, although it doesn't have quite the same velocity as a four-seam fastball. A two-seam fastball is one of the most frequently thrown pitches in baseball.

A two-seam fastball is often a few ticks slower than a four-seam fastball, but it tends to have more movement. With a two-seamer, the ball moves in the same direction as whichever arm is being used to throw it (meaning a right-handed pitcher gets rightward movement on a two-seamer).

Grip

There are a variety of grips that pitchers use to throw two-seam fastballs, but the most common occurs when the pitcher puts his two fingers directly on top of the part of the ball where the seams are closest together.

If thrown with the same finger pressure, two-seam and four-seam fastballs can look similar. However, two-seam fastballs usually aren't thrown with the same finger pressure as a four-seamer. Finger pressure plays a large role in determining pitch movement.

Two-seam fastballs are especially useful for pitchers who lack the raw velocity to overpower hitters. The movement and deception on the pitch, coupled with its speed, can often make up for that slight dip in velocity.

In A Call

"two-seamer," "moving fastball," "running fastball"

Source: MLB

Two-way Players

Prior to the 2020 season, Major League Baseball instituted a rule requiring all MLB teams to designate every player on the active roster as either a pitcher or a position player. Those designated as position players would have been unable to pitch unless it was extra innings, their team was ahead or trailing by more than six runs, or they had qualified as a two-way player.

Per the rule, a position player was able to qualify for two-way status if he had:

1) Pitched at least 20 Major League innings AND
2) Played at least 20 Major League games as a position player or designated hitter, with at least three plate appearances in each game, in either the current or previous MLB season.

As part of MLB's health and safety protocols amid the COVID-19 pandemic, this rule was not utilized during the 2020 and 2021 seasons.

Source: MLB

U

Ultimate Zone Rating (UZR)

UZR quantifies a player's entire defensive performance by attempting to measure how many runs a defender saved. It takes into account errors, range, outfield arm and double-play ability. It differs slightly from DRS (Defensive Runs Saved) in its formula, but the concept is the same.

The formula

UZR uses Baseball Info Solutions data to chart where each ball is hit. Say, for instance, a center fielder sprints to make a nice catch on a fly ball. Then, say data from BIS tells us that similar fly balls get caught 60 percent of the time. That center fielder gains, essentially, 0.4 bonus points for difficulty. If he can't make the play, he loses 0.6 points. At the end of the day, that player's overall score gets adjusted to the league average -- and then that score gets adjusted for how many runs the once-adjusted score is worth.

Why it's useful

Like Defensive Runs Saved (DRS), UZR provides a more in depth way to evaluate fielders than some traditional defensive stats do.

Source: MLB

Umpire

Umpires are responsible for enforcing on-field rules and rendering decisions on judgment calls such as: Whether a batter or baserunner is safe or out, and whether a pitched baseball is a strike or a ball.

A regular-season contest will have four umpires: one behind home plate and one stationed near each of the other three bases. Each umpire makes "out" or "safe" decisions at his designated base, and the home-plate umpire is responsible for calling balls and strikes on each pitch that is thrown. The first-base umpire determines whether batted balls were hit into fair or foul territory down the right-field line past the first-base bag, with the third-base umpire doing the same on balls hit down the left-field line beyond the third-base bag. Umpires at first and third base can also assist the home-plate umpire in determining whether a batter offered at a pitch or "checked his swing." If the latter is determined, a pitch outside the strike zone is recorded as a ball.

Umpires also have the jurisdiction to eject players, coaches or managers who break certain rules or do not display proper on-field conduct.

Unlike the umpires stationed in the field, the home-plate umpire stands behind the plate and wears a facemask and a heavy chest pad in order to protect against batted balls that are fouled directly backward.

During postseason contests, Major League Baseball adds left-field and right-field umpires to help ensure accurate calls on baseballs hit down the fair/foul lines. Umpires stationed in the outfield can also assess if a batted ball hit in their vicinity was caught on the fly or trapped in a fielder's glove after bouncing on the grass.

Major League Baseball also employs replay officials -- full-time Major League umpires who work shifts in the Replay Command Center in New York. Replay officials review all calls subject to replay review and decide whether to change the call on the field, confirm the call on the field or let stand the call on the field due to the lack of clear and convincing evidence. Replay officials also work as on-field umpires during the season.

Source: MLB

Unearned Run (UER)

An unearned run is any run that scored because of an error or a passed ball. Oftentimes, it is the judgment of the official scorer as to whether a specific run would've scored without the defensive mishap.

The purpose of the unearned run is to distinguish which runs a pitcher is at fault for allowing. Unearned runs do not count against a pitcher's ERA. However, there are a few flaws with ignoring unearned runs when evaluating a pitcher. First, it's a pitcher's job to prevent runs -- not to simply prevent earned runs. Second, not every error is created equal -- and some plays that are ruled as hits can be a product of subpar defense.

Although unearned runs don't hurt a pitcher's ERA, they can hurt a pitcher in other ways -- namely in his quest to win. Every error means a bigger burden on the pitcher in terms of pitches thrown. In this regard, unearned runs can often lead to an early exit for a pitcher.

An unearned run can never take place without the occurrence of an error or a passed ball.

In A Call

"cheapie," "run scored due to error"

Source: MLB

V

Velocity (VELO)

Velocity, one of the most frequently used tools for evaluating pitchers, represents the maximum speed of a given pitch at any point from its release to the time it crosses home plate.

Prior to the advent of Statcast, pitch tracking in every MLB stadium was performed by PITCHf/x. One way this system differed from Statcast is that it reported the Velocity of each pitch when it was 50 feet from the back tip of home plate, rather than at the release point. To produce Velocity readings that were closer to pitchers' actual release points, some entities began using 55 feet as the point of reference, inferring what the velocity would be at 55 feet based on the PITCHf/x data for the reported velocity at 50 feet.

Conversely, Statcast can provide the maximum speed of a pitch at any point in its flight -- with the max speed always being at the release point, due to physics -- which allows for a more precise measurement of pitch velocity.

In A Call

"pitch speed," "velo," "mph"

Source: MLB

Vesting Option

A vesting option is an optional year at the end of the contract that becomes guaranteed if the player reaches a certain performance incentive threshold. Vesting options are typically based on playing time incentives such as plate appearances, innings pitched, games started or games finished. In most cases, a vesting option that fails to vest can still be exercised as a club option.

Example

Santiago Casilla played the final guaranteed season of a three-year contract with the Giants in 2015, but he had a vesting option for the '16 season that went into effect when he reached 55 games finished. Casilla finished exactly 55 games, automatically locking in his salary for '16.

Source: MLB

W

Walk (BB)

A walk (or base on balls) occurs when a pitcher throws four pitches out of the strike zone, none of which are swung at by the hitter. After refraining from swinging at four pitches out of the zone, the batter is awarded first base. In the scorebook, a walk is denoted by the letters BB.

As a stat, walks can be used to measure two of the game's most important skills: a pitcher's control and a hitter's eye (meaning his ability to tell whether a pitch is a strike or a ball and swing -- or not swing -- accordingly). Because both of these factors are extremely important in the process, walks are looked at as a stat for both pitchers and hitters.

The game's better hitters earn a higher number of walks because pitchers tend to avoid throwing them hittable pitches, and because their keen eye allows them to lay off pitches that narrowly miss the strike zone. Sometimes, a pitcher will opt not to pitch to a hitter altogether, purposely walking him. This is called an "intentional walk," though it still counts as a regular walk for record-keeping purposes

In A Call

"base on balls," "free pass," "put him on"

Source: MLB

Walk Rate (BB%)

Walk rate represents the frequency with which a pitcher walks hitters, as determined by total walks divided by total batters faced. It's an important tool for assessing a pitcher's capabilities and perhaps the most important in judging a pitcher's tendency to walk batters.

Obviously, one of a pitcher's primary goals is to avoid putting hitters on base, and by walking hitters, he's doing just that. Unlike batted balls -- where the outcome is largely a result of team defense and luck -- walks are a surefire way to allow baserunners.

In A Call

"walk percentage"

Source: MLB

Walk-off

A "walk-off" is any offensive play that gives the home team the lead -- and thus, the win -- in the bottom of the last inning.

Origin

The term walk-off originated as "walk-off piece," and was coined by Hall of Famer Dennis Eckersley. ''It was always walk-off piece," Eckersley told the Boston Globe. "Like something you would hang in an art gallery. The walk-off piece is a horrible piece of art."

The first reference to walk-off came in a July 30, 1988, story in the Gannett News Service: "In Dennis Eckersley's colorful vocabulary, a walk-off piece is a home run that wins the game and the pitcher walks off the mound."

Walk-off piece was only intended to describe a pitcher's dejected walk off the field after giving up a game-losing home run, but it soon grew into its own phenomenon.

Source: MLB

Walk-off (WO)

A walk-off occurs when the home team takes the lead in the bottom of the ninth or extra innings. Because the visiting team will not get another turn at-bat, the game ends immediately, with the home team victorious.

A walk-off can be recorded in many ways, including: a hit, an error, a walk with the bases loaded, a hit by pitch with the bases loaded, a sacrifice fly, an out (with less than two outs in the inning), a wild pitch, a passed ball and a balk. As long as enough runs are scored to end the game as the result of the play, it is considered a walk-off.

In walk-off situations with fewer than two outs and a runner on third base, a visiting team will typically adjust its defense to maximize the chances of stopping a runner at home plate. The visitors typically bring the infield in, so the infielders are positioned closer to home plate. Sometimes, a manager will even bring one of his outfielders into the infield to maximize the chances of throwing home for an out on a ground ball. Outfielders will almost always play very shallow to have a chance at a double play on a flyout or to throw the runner out at home on a single.

A walk-off is almost always celebrated by the home team, with its players mobbing the contributor who recorded the game-winning plate appearance. Because a walk-off can only occur in the game's final half inning, the visiting team cannot record a walk-off in any situation.

Origin

The term walk-off was originally coined by pitcher Dennis Eckersley to describe game-ending home runs that were so deep, you didn't have to look at them as a pitcher. You just "walked off." Since then, the term has evolved to connote a situation where the game ends, with the losing team left to "walk off" the field in defeat.

In A Call

"game-winner," "winner," "sudden victory," "game-ender"

Source: MLB

Walks And Hits Per Inning Pitched (WHIP)

WHIP is one of the most commonly used statistics for evaluating a pitcher's performance. The statistic shows how well a pitcher has kept runners off the basepaths, one of his main goals. The formula is simple enough -- it's the sum of a pitcher's walks and hits, divided by his total innings pitched.

The pitchers with the lowest WHIPs are generally the best pitchers in the league -- which makes sense, because the best pitchers should be able to prevent baserunners. However, WHIP does not consider the way in which a hitter reached base. (Obviously, home runs are more harmful to pitchers than walks.)

Hit batsmen, errors and hitters who reach via fielder's choice do not count against a pitcher's WHIP.

Origin

Daniel Okrent, a writer who invented rotisserie league fantasy baseball, coined the term in 1979, initially calling it innings pitched ratio. The term eventually developed into WHIP.

In A Call

"whip" -- as an acronym, not spelled out

Source: MLB

Walks Per Nine Innings (BB/9)

Walks per nine innings tells us how many walks a given pitcher allows per nine innings pitched -- using the formula walks divided by innings times nine.

Obviously, a pitcher's goal is to keep opposing batters off the bases -- and a walk does just the opposite of that. If he allows a ball in play, he at least puts the outcome in the hands of his defense -- and luck. But a walk gives the team behind him no chance to help.

In A Call

"walks per nine," "walk rate per nine," "walks per game"

Source: MLB

Warmup Pitches

When taking their position at the beginning of an inning or when relieving another pitcher, pitchers are permitted to throw as many warmup pitches as they want within the countdown parameters set forth by Major League Baseball.

The time between innings and pitching changes is 2 minutes, 5 seconds for local broadcasts, 2 minutes, 25 seconds for nationally televised games and 2 minutes, 55 seconds for tiebreaker and postseason games. The umpire's signal for the final warmup pitch comes at the 25-second mark and the pitcher must throw it before the clock hits 20. The batter will be announced at the 20-second mark and the pitcher must begin his windup to throw the first pitch of the inning within the five seconds before the clock hits zero.

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