Traditionally, statistics such as batting average (the number of hits divided by the number of at bats) and earned run average (the average number of earned runs allowed by a pitcher per nine innings) have dominated attention in the statistical world of baseball. However, the recent advent of sabermetrics has created statistics drawing from a greater breadth of player performance measures and playing field variables. Sabermetrics and comparative statistics attempt to provide an improved measure of a player's performance and contributions to his team from year to year, frequently against a statistical performance average.
Comprehensive, historical baseball statistics were difficult for the average fan to access until 1951, when researcher Hy Turkin published The Complete Encyclopedia of Baseball. In 1969, Macmillan Publishing printed its first Baseball Encyclopedia, using a computer to compile statistics for the first time. Known as "Big Mac", the encyclopedia became the standard baseball reference until 1988, when Total Baseball was released by Warner Books using more sophisticated technology. The publication of Total Baseball led to the discovery of several "phantom ballplayers", such as Lou Proctor, who did not belong in official record books and were removed.
Throughout modern baseball, a few core statistics have been traditionally referenced – batting average, RBI, and home runs. To this day, a player who leads the league in all of these three statistics earns the "Triple Crown". For pitchers, wins, ERA, and strikeouts are the most often-cited statistics, and a pitcher leading his league in these statistics may also be referred to as a "triple crown" winner. General managers and baseball scouts have long used the major statistics, among other factors and opinions, to understand player value. Managers, catchers and pitchers use the statistics of batters of opposing teams to develop pitching strategies and set defensive positioning on the field. Managers and batters study opposing pitcher performance and motions in attempting to improve hitting. Scouts use stats when they are looking at a player who they may end up drafting or signing to a contract.
Some sabermetric statistics have entered the mainstream baseball world that measure a batter's overall performance including on-base plus slugging, commonly referred to as OPS. OPS adds the hitter's on-base percentage (number of times reached base by any means divided by total plate appearances) to their slugging percentage (total bases divided by at-bats). Some argue that the OPS formula is flawed and that more weight should be shifted towards OBP (on-base percentage). The statistic wOBA (weighted on-base average) attempts to correct for this.
OPS is also useful when determining a pitcher's level of success. "Opponent on-base plus slugging" (OOPS) is becoming a popular tool to evaluate a pitcher's actual performance. When analyzing a pitcher's statistics, some useful categories include K/9IP (strikeouts per nine innings), K/BB (strikeouts per walk), HR/9 (home runs per nine innings), WHIP (walks plus hits per inning pitched), and OOPS (opponent on-base plus slugging).
However, since 2001, more emphasis has been placed on defense-independent pitching statistics, including defense-independent ERA (dERA), in an attempt to evaluate a pitcher's performance regardless of the strength of the defensive players behind them.
All of the above statistics may be used in certain game situations. For example, a certain hitter's ability to hit left-handed pitchers might incline a manager to increase their opportunities to face left-handed pitchers. Other hitters may have a history of success against a given pitcher (or vice versa), and the manager may use this information to create a favorable
match-up. This is often referred to as "playing the percentages".
Commonly used statistics
Most of these terms also apply to softball. Commonly used statistics with their abbreviations are explained here. The explanations below are for quick reference and do not fully or completely define the statistic; for the strict definition, see the linked article for each statistic.
1B – Single: hits on which the batter reaches first base safely without the contribution of a fielding error
2B – Double: hits on which the batter reaches second base safely without the contribution of a fielding error
3B – Triple: hits on which the batter reaches third base safely without the contribution of a fielding error
AB – At bat: plate appearances, not including bases on balls, being hit by pitch, sacrifices, interference, or obstruction
ITPHR – Inside-the-park home run: hits on which the batter successfully touched all four bases, without the contribution of a fielding error or the ball going outside the ball park.
IBB – Intentional base on balls: times awarded first base on balls (see BB above) deliberately thrown by the pitcher. Also known as IW (intentional walk).
ISO – Isolated power: a hitter's ability to hit for extra bases, calculated by subtracting batting average from slugging percentage
K – Strike out (also abbreviated SO): number of times that a third strike is taken or swung at and missed, or bunted foul. Catcher must catch the third strike or batter may attempt to run to first base.
LOB – Left on base: number of runners neither out nor scored at the end of an inning
OBP – On-base percentage: times reached base (H + BB + HBP) divided by at bats plus walks plus hit by pitch plus sacrifice flies (AB + BB + HBP + SF)
TA – Total average: total bases, plus walks, plus hit by pitch, plus steals, minus caught stealing divided by at bats, minus hits, plus caught stealing, plus grounded into double plays [(TB + BB + HBP + SB – CS)/(AB – H + CS + GIDP)]
TB – Total bases: one for each single, two for each double, three for each triple, and four for each home run [H + 2B + (2 × 3B) + (3 × HR)] or [1B + (2 × 2B) + (3 × 3B) + (4 × HR)]
TOB – Times on base: times reaching base as a result of hits, walks, and hit-by-pitches (H + BB + HBP)
BK – Balk: number of times pitcher commits an illegal pitching action while in contact with the pitching rubber as judged by umpire, resulting in baserunners advancing one base
BS – Blown save: number of times entering the game in a save situation, and being charged the run (earned or not) which eliminates his team's lead
CERA – Component ERA: an estimate of a pitcher's ERA based upon the individual components of his statistical line (K, H, 2B, 3B, HR, BB, HBP)
CG – Complete game: number of games where player was the only pitcher for their team
DICE – Defense-Independent Component ERA: an estimate of a pitcher's ERA based upon the defense-independent components of his statistical line (K, HR, BB, HBP) but which also uses number of outs (IP), which is not defense independent.
ER – Earned run: number of runs that did not occur as a result of errors or passed balls
ERA – Earned run average: total number of earned runs (see "ER" above), multiplied by 9, divided by innings pitched
FIP – Fielding independent pitching: a metric, scaled to resemble an ERA, that focuses on events within the pitcher's control – home runs, walks, and strikeouts – but also uses in its denominator the number of outs the team gets (see IP), which is not entirely within the pitcher's control.
xFIP: This variant substitutes a pitcher's own home run percentage with the league average
G – Games (AKA "appearances"): number of times a pitcher pitches in a season
GF – Games finished: number of games pitched where player was the final pitcher for their team as a relief pitcher
GIDP – Double plays induced: number of double play groundouts induced
GIDPO – Double play opportunities: number of groundout induced double play opportunities
L – Loss: number of games where pitcher was pitching while the opposing team took the lead, never lost the lead, and went on to win
LOB% – Left-on-base percentage: LOB% represents the percentage of baserunners a pitcher does not allow to score. LOB% tends to regress toward 70–72% over time, so unusually high or low percentages could indicate that pitcher's ERA could be expected to rise or lower in the future. An occasional exception to this logic is a pitcher with a very high strikeout rate.
pNERD – Pitcher's NERD: expected aesthetic pleasure of watching an individual pitcher
QOP – Quality of pitch: comprehensive pitch evaluation statistic which combines speed, location and movement (rise, total break, vertical break and horizontal break) into a single numeric value
QS – Quality start: a game in which a starting pitcher completes at least six innings and permits no more than three earned runs
RA – Run average: number of runs allowed times nine divided by innings pitched
SHO – Shutout: number of complete games pitched with no runs allowed
SIERA – Skill-Interactive Earned Run Average: another advanced stat that measures pitching. SIERA builds on FIP and xFIP by taking a deeper look at what makes pitchers better.
SV – Save: number of games where the pitcher enters a game led by the pitcher's team, finishes the game without surrendering the lead, is not the winning pitcher, and either (a) the lead was three runs or fewer when the pitcher entered the game; (b) the potential tying run was on base, at bat, or on deck; or (c) the pitcher pitched three or more innings
SVO – Save opportunity: When a pitcher 1) enters the game with a lead of three or fewer runs and pitches at least one inning, 2) enters the game with the potential tying run on base, at bat, or on deck, or 3) pitches three or more innings with a lead and is credited with a save by the official scorer
W – Win: number of games where pitcher was pitching while their team took the lead and went on to win, also the starter needs to pitch at least 5 innings of work (also related: winning percentage)
W + S – Wins in relief + saves.
whiff rate: a term, usually used in reference to pitchers, that divides the number of pitches swung at and missed by the total number of swings in a given sample. If a pitcher throws 100 pitches at which batters swing, and the batters fail to make contact on 26 of them, the pitcher's whiff rate is 26%.
It is difficult to determine quantitatively what is considered to be a "good" value in a certain statistical category, and qualitative assessments may lead to arguments. Using full-season statistics available at the Official Site of Major League Baseball for the 2004 through 2015 seasons, the following tables show top ranges in various statistics, in alphabetical order. For each statistic, two values are given:
Top5: the top five players bettered this value in all of the reported seasons
Best: this is the best of all of the players for all of the reported seasons
^Palmer, Pete; Paul Adomites; David Nemec; Matthew D. Greenberger; Dan Schlossberg; Dick Johnson; Mike Tully (2001). "Birth of the Game". Cooperstown: Hall of Fame Players. Lincolnwood, Illinois: Publications International. p. 21. ISBN0-7853-4530-2.
Albert, Jim, and Jay M. Bennett. Curve Ball: Baseball, Statistics, and the Role of Chance in the Game. New York: Copernicus Books, 2001. ISBN0-387-98816-5. A book on new statistics for baseball. MLB Record Book by: MLB.com