Baseball Stats

Ground Into Double Play (GIDP)

A GIDP occurs when a player hits a ground ball that results in multiple outs on the bases.

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.

Plate Appearances Per Strikeout (PA/SO)

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.

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.

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.

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.

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.

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.

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.

Double Play (DP)

A double play occurs when two offensive players are ruled out within the same play.

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.

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.

Flyout (AO)

A flyout occurs when a batter hits the ball in the air and an opposing defender catches it before it hits the ground or fence.

Grand Slam (GSH)

A grand slam occurs when a batter hits a home run with men on first base, second base and third base.

Groundout (GO)

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."

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.

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.

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.

Complete Game (CG)

A pitcher earns a complete game if he pitches the entire game for his team regardless of how long it lasts.

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.

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.

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.

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.

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.

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.

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.

Pitches Per Plate Appearance (P/PA)

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.

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.

Batting Average (AVG)

A stat determined by dividing a player's hits by his total at-bats for a number between zero (shown as .000) and one (1.000).

Range Factor (RF)

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

Defensive Efficiency Ratio (DER)

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?

Stolen Base (SB)

A stolen base occurs when a baserunner advances by taking a base to which he isn't entitled.

Triple (3B)

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.

Triple Play (TP)

A triple play occurs when the defending team records three outs on a single defensive play.

Walk (BB)

A walk 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.

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.

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.

Earned Run (ER)

An earned run is any run that scores against a pitcher without the benefit of an error or a passed ball.

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.

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 count as a walk for the batter and a walk allowed for the pitcher.

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.

Outfield Assist (OFA)

An outfielder records an assist when he throws the ball into the infield and an out is recorded as a result.

Late-inning Pressure Situation (LIPS)

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.

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).

Ballpark Factor (BPF)

BPF indicates the difference between runs scored in a team's home and road games.

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.

Batters Faced (BF)

Batters faced is simply a count of the number of total plate appearances against a certain pitcher or team.

Bequeathed Runners (BQR)

Bequeathed runners represents the number of runners left on base by a pitcher when that pitcher leaves the game. It's often used as a statistic when assessing a starting pitcher's luck regarding his ERA, because any bequeathed runners who score an earned run after a pitcher has left the game will negatively affect his ERA.

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.

Caught Stealing Percentage (CS%)

Caught stealing percentage refers to the frequency with which a catcher throws out opposing baserunners who are trying to steal. The formula is simple: catcher caught stealings divided by total stolen-base attempts -- both successful and unsuccessful -- against that catcher.

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.

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.

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.

Runs Created (RC)

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.

Inherited Runs Allowed (IR-A)

Every inherited runner who scores when a relief pitcher is in the game counts as an inherited run allowed against that relief pitcher. It's a way of quantifying how well a reliever performs when thrown into a situation with men already on base. (This is somewhat necessary, for evaluation purposes, because those runs won't be charged against that relief pitcher's ERA.)

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.

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).

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.)

Game Score

Game Score measures a pitcher's performance in any given game started. 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.

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.

Groundout-to-Flyout Ratio (GO/AO)

Groundout-to-flyout ratio is obtained by dividing the total number of ground balls converted into outs (not including bunts), by the total of all fly balls converted into outs.

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.

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.

Home Run To Fly Ball Rate (HR/FB)

Home-run-per-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.

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?

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.

Left On Base (LOB)

In an individual batter's case, it refers to how many men remain on base after that batter makes an out at the plate. 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.

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.

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.

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. Obviously, a high number is preferable because it generally means success, and because longer outings from a starter lead to more rest for a bullpen.

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.

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.

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.

Leverage Index (LI)

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.

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.

On-base Percentage (OBP)

OBP refers to how frequently a batter reaches base per plate appearance. Times on base include hits, walks and hit-by-pitches, but do not include errors, times reached on a fielder's choice or a dropped third strike.

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.

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.

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.

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.

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.

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.)

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?"

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.

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.

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.

Stolen-base Percentage (SB%)

Stolen-base percentage is determined by the number of steals for a player divided by his total number of attempts.

Strikeout Rate (K%)

Strikeout rate represents the frequency with which a pitcher strikes out hitters, as determined by total strikeouts divided by total batters faced. It's perhaps the most accurate tool for judging a pitcher's ability to strike out hitters.

Total Bases (TB)

Total bases refer to the number of bases gained by a batter through his hits.

True Earned Run Average (tERA)

True Earned Run Average, like FIP, attempts to quantify a pitcher's performance based on what he can control. But unlike FIP -- which factors only home runs, strikeouts, walks and HBPs -- tERA also accounts for batted-ball tendencies. That means pitchers who record mostly ground balls and popups, as opposed to line drives and fly balls, are rewarded for inducing weaker contact.

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.

Wins Above Replacement (WAR)

WAR measures a player's value in all facets of the game by deciphering how many more wins he's worth than a replacement-level player at his same position (e.g., a Minor League replacement or a readily available fill-in free agent).

Win Probability Added (WPA)

WPA quantifies the percent change in a team's chances of winning from one event to the next. It does so by measuring the importance of a given plate appearance in the context of the game. For instance: a homer in a one-run game is worth more than a homer in a blowout.

Walk Rate (BB%)

Walk rate represents the frequency with which a pitcher walks hitters, as determined by total walks divided by total batters faced.

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.

Win Expectancy (WE)

Win Expectancy (WE), otherwise known as Win Probability, indicates the chance a team has to win a particular game at a specific point in that game.

Weighted On-base Average (wOBA)

wOBA is a version of on-base percentage that accounts for how a player reached base -- instead of simply considering whether a player reached base. The value for each method of reaching base is determined by how much that event is worth in relation to projected runs scored (example: a double is worth more than a single).

Weighted Runs Above Average (wRAA)

wRAA measures how many runs a hitter contributes, compared with an average player -- so a player with a 0 wRAA would be considered league average, offensively. It's calculated by finding the difference in the number of runs contributed between a player and the league average (which is determined by the league average wOBA).

Weighted Runs Created Plus (wRC+)

wRC+ takes the statistic Runs Created and adjusts that number to account for important external factors -- like ballpark or era. It's adjusted, so a wRC+ of 100 is league average and 150 would be 50 percent above league average.

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.