Glossary: Offense

For hitters: Singles

For pitchers: Singles Allowed

For positions: First Baseman

For hitters: Doubles
For pitchers: Doubles Allowed
For positions: Second Baseman

For hitters: Triples
For pitchers: Triples Allowed
For positions: Third Baseman

Official plate appearances where the batter doesn't walk, get hit by a pitch, hit a recognized sacrifice or is interfered with by the catcher.

Hitters: Batting average
Pitchers: Batting average allowed

Singles per plate appearance

Doubles per plate appearance

Triples per plate appearance

A pitcher's average on batted balls ending a plate appearance, excluding home runs. Based on the research of Voros McCracken and others, BABIP is mostly a function of a pitcher's defense and luck, rather than persistent skill. Thus, pitchers with abnormally high or low BABIPs are good bets to see their performances regress to the mean. The league average for modern pitcher BABIP is around .300.

Hitter BABIP is much more of a skill, based on how well they are able to hit and place the ball, along with their speed.

Equation:

BABIP = (H - HR) / (AB - K - HR + SF + SH)

Hitters: Base on balls (walks)
Pitchers: Base on balls (walks) allowed

Batters Left On Base

BPF is centered around 100, with numbers above and below representing percentage that run-scoring was increased by the mix of parks the batter batted in. For instance, 110 represents 10% above average and 96 represents 4% below average.

Baserunning Runs. Measures the number of runs contributed by a player's advancement on the bases, above what would be expected based on the number and quality of the baserunning opportunities with which the player is presented, park-adjusted and based on a multi-year run expectancy table. BRR is calculated as the sum of various baserunning components: Ground Advancement Runs (GAR), Stolen Base Runs (SBR), Air Advancement Runs (AAR), Hit Advancement Runs (HAR) and Other Advancement Runs (OAR).

Here is an example of the Baserunning Runs spectrum based on the 2011 season:

Excellent - Ian Kinsler 11.6
Great - Coco Crisp 4.3
Average - Bobby Abreu 0.0
Poor - Casey Kotchman -4.4
Horrendous - Ryan Howard -9.4


Note: Credit/blame for Double plays is not ascribed to either batter or runner(s) via BRR. Hence Manny Machado can lead MLB in GIDP in 2018 yet have almost +1 BRR. Or Tommy Pham with 18 GIDP in 570 PA and almost +5 BRR.

Value over Replacement Player (VORP) as a batter, in runs. This is equal to VORP for batters who did not pitch.

Wins Above Replacement Player (WARP) gained as a non-pitcher. This includes hitting and fielding.

Number of balls seen (batter) or thrown (pitcher)

The number of runs a player has batted in other than himself.

BATTED_IN=RBI-HR

Batting average; hits divided by at-bats. In PECOTA, Batting Average is one of five primary production metrics used in identifying a hitter's comparables. It is defined as H/AB.

Complete Games.

CS are not available for the NL from 1876-1950 (except for 1915, 1920-25, and some players for 1916), in the AL from 1901-19 (except 1914-15 and some 1916 players), and are not available at all for the AA, UA, PL, or FL. Surprisingly, they are available for the NA. In catcher's fielding, not available prior to 1978.

Double plays, turned or hit into.

The percent of the time the double play opportunities (DP_OPPS) were converted into double plays (DP)

The number of double play opportunities (defined as less than two outs with runner(s) on first, first and second, or first second and third).

Learn more about DRC+ at our DRC+ Showcase page.

Traditional metrics compromise accuracy in two ways: (1) they summarize play outcomes in which players were involved, not player contributions to those outcomes; and (2) they treat all outcomes as equally likely to be driven by the player, even though no one believes that is true.

DRC+ addresses the first problem by rejecting the assumption that play outcomes equal player contributions, and forces players to demonstrate a consistent ability to generate those outcomes over time to get full credit for them. DRC+ addresses the second problem by recognizing that certain outcomes (walks, strikeouts) are more attributable to player skill than others (singles, triples). DRC+ gives more weight to extreme performances in the former (because they are probably meaningful) and less weight to extreme performances in the latter (because they are less likely to be meaningful). By addressing these two deficiencies in existing metrics, DRC+ ends up being substantially more reliable and predictive than any other baseball hitting metric. (The PA-level opponent and park adjustments don’t hurt either). The Top 15 undervalued players are not “undervalued” in the sense that they are hidden Hall of Famers; they get undervalued by OPS / wOBA / SLG / wRC+ / whatever because those metrics do not weight each event by the likelihood it was driven by the player himself, as opposed to random variance.

A player like Alberto Callaspo has somewhat extreme numbers in metrics DRC+ considers uniquely likely to be driven by the player: healthy walk rates and exceptionally low strikeout rates. Callaspo saved runs every year, on average, by striking out very infrequently. He was above average in walks for a while, although not every season. One consequence of not striking out so much is that he was hitting more singles, and consistently gets credit for hitting more singles than average. The point isn’t that Callaspo is some great player: it is that DRC+ better understands how “real” his contributions were than other metrics, because the latter make no effort to distinguish the various aspects of his game. It brings the same, more sophisticated perspective to other players also.

Deserved Runs Above Average - Runs above average for a hitter (RAA) based on the DRC+ model. This is used in the computation of Batter WARP. An introduction to the DRC+ statistic is here: https://www.baseballprospectus.com/news/article/45432/why-drc/

Rate version of END_GAME: percentage of the player's plate appearances that were the last PA of the game.

Number of times the player had the last plate appearance of the game.

In player or team statistical context, batted balls that were classified as ground balls.

In team standings context, Games Back. How far this team is behind the team leading the division. The formula is

((Division Leader's Wins - This team's Wins) + (This team's Losses - Division Leader's Losses)) / 2

The Division Leader is the team with the highest team Wins minus team Losses. GB is traditionally expressed as a dash (-) for the division leader and a whole or half number for teams behind that team. For teams lagging the Division Leader, a win or a Division Leader Loss will reduce their GB by half a game.

GB is not recalculated for League or All MLB groupings; it always reflects a team's status relative to the leader of their division.

Grounded into double play. Not recorded prior to 1933 in the NL, or 1939 in the AL, and not at all for the other leagues. Unfortunately, without opportunity information, I don't find it very useful for inclusion in EqA. There is also evidence, from Tom Ruane, that players who hit into more DP also tend to advance more runners with outs, enough to offset the DPs.

Named after manager Ozzie Guillen by Joe Sheehan, because Guillen's White Sox teams have owed much more of their scoring to homers than to the one-run strategies to which their success was often attributed. For historical backgrounds, see here.

Hits, or hits allowed.

Not recorded for the NL 1876-1886, the AA in 1882-83, the 1884 UA, and the 1871-75 NA, for either hitters or pitchers.

Hit By Pitch Rate -- HBP per plate appearance

Hit Rate -- hits per plate appearance

Home runs, or home runs allowed.

Not recorded for any league prior to 1955.

Number of times a player led off an inning, as a rate of his total PA.

Number of times the player led off an inning.

The number of additional double plays generated versus an average player with the same number of opportunities. Negative NET DP indicates that fewer double plays than average were produced.

Non-Strikeout Out Rate -- batting outs (other than by strikeout, i.e. outs on balls in play) per plate appearance.

Others Batted In -- runs batted in, except for the batter driving himself in via a home run. Equal to RBI-HR

Others Batted In Percentage. Percentage of all runners on base batted in.

On-base percentage. (H + BB + HBP) divided by (AB + BB + HBP + SF). For pitchers, OBP is on base percentage allowed.

Opponent's Quality, Batting Average -- the aggregate batting average of all batters faced (by a pitcher), or allowed by all pitchers faced (for a batter)

Opponent's Quality, On-Base Percentage -- the aggregate onbase percentage of all batters faced (by a pitcher), or allowed by all pitchers faced (for a batter)

Opponent's Quality, On-Base plus Slugging Average -- the aggregate OPS of all batters faced (by a pitcher), or allowed by all pitchers faced (for a batter)

Opponent's Quality, Slugging Average -- the aggregate slugging average of all batters faced (by a pitcher), or allowed by all pitchers faced (for a batter)

Opponent's Quality, True Average -- the aggregate True Average of all batters faced (by a pitcher), or allowed by all pitchers faced (for a batter).

On Base Percentage + Slugging Percentage

Out Rate. Batting outs per plate appearance.

Known outs made by the player or induced by a pitcher, defined by AB-H+CS+SH+SF.

Plate appearances; AB + BB + HBP + SH + SF.

The percentage of the team's total plate appearances that this player had.

Plate appearances at the position of first base

Plate appearances at the position of second base

Plate appearances at the position of third base

Plate appearances at the position of catcher

Plate appearances at the position of center field

Plate appearances as a designated hitter

Plate appearances at the position of left field

Plate appearances at the position of pitcher

Plate appearances as a pinch hitter

Plate appearances as a pinch runner

Plate appearances at the position of right field

Plate appearances with runners on base

Plate appearances at the position of shortstop

Number of times picked off

Number of pitches seen (batter) or thrown (pitcher)

Complete statistical data is available for:

• Batters vs left-handed pitchers (LHP)
• Batters vs right-handed pitchers (RHP)
• Pitchers vs left-handed batters (LH)
• Pitchers vs right-handed batters (RH)

For PECOTA, a player's Position is a consideration in identifying his comparables, as well as in calculating his VORP. The player's primary position as used by PECOTA is listed at the top of his forecast page; however, secondary and tertiary positions are also considered based on the relative amount of appearances that a player receives there. The position determination is made primarily based on the position(s) that a player appeared in his most recent season, with lesser consideration given to the position(s) he appeared other recent previous seasons. Both major league and minor league defensive appearances are considered in the determination of a player's position, but major league appearances are weighted more heavily. PECOTA considers LF, CF and RF to be separate positions.

When listed numerically on our statistical reports, positions are: 1, pitcher; 2, catcher; 3, first base; 4, second base; 5, third base; 6, shortstop; 7, left field; 8, center field; 9, right field; 10, designated hitter; 11, pinch hitter; 12, pinch runner.

Runs scored (for hitters) or allowed (pitchers).

Runner on first. In the RBI opportunity report, refers to the number of times a batter came to the plate with a runner at first base.

Percentage of runners on first base batted in

Runners on first base batted in

Runner on second. In the RBI opportunity report, refers to the number of times the batter came to the plate with a runner at second base.

Percentage of runners on second base batted in

Runners on second base batted in

Runner on third. In the RBI opportunity report, refers to the number of times the batter came to the plate with a runner at third base.

Percentage of runners on third base batted in

Runners on third base batted in

Runs Batted In.

Number of runs a batter has driven in per runner on base during a batter's plate appearances. Defined as total baserunners/RBI (NB: Runners on base are other than the batter himself--RBI's resulting from a batter driving himself in on home runs are removed).

RBI + R - HR. Used in fantasy baseball to approximate runs created in a simple fashion.

RBI Rate -- RBI per plate appearance

Runners On Base: the number of runners on base during a batter's plate appearances.

Reached On Error: when a batter reaches base as a direct result of a fielding error.

Percentage of plate appearances that result in the batter reaching base on an error.

Reached On Error Rate -- reaching on error per plate appearance.

RPA+ is computed as: RPA/lgRPA Where lgRPA is the league runs per plate appearance, adjusted to match a player's run environment (adjusted for park, in other words). The scale of RPA+ should correspond with that of OPS+ and similar metrics; it will produce the same rank order as True Average, however. Read more here

Actual runs scored by a team.

Runs scored Rate -- Runs scored (typically by a player) per plate appearance

Stolen bases. Not recorded for any league between 1876 and 1885. On the catcher's fielding charts, not available prior to 1978.

Sacrifice flies. The statistical category of "sacrifice flies" did not exist prior to 1954; the concept had been around, on and off, since 1908, but had been always been part of the "SH" category. See SH.

Sacrifice hits. Not recorded prior to 1894. From 1894-1907, they were essentially the same as the modern rule - a bunt which advanced a baserunner. From 1908-25, they included what we would now call a sacrifice fly (sacrifices increase 25% between 1907 and 1908 as a result). From 1926-30, they included any fly ball on which a runner advanced, not just ones where the runner scored (another 25% increase in 1926). From 1931-38, sacrifice flies were eliminated completely (causing a 45% drop in sacrifices, and a 4-point decline in batting averages); that brought us back to the modern definition of sacrifice hit. In 1939 they re-introduced the run-scoring sac fly (returning to the 1908-25 rules), but eliminated it again in 1940. When sacrifice flies appeared again in 1954, they had their own category, so the rule for what we would call a sacrifice hit has not changed since 1940.

Sacrifice Hit Rate -- Sacrifices per plate appearance

Slugging percentage (hitters) or slugging percentage allowed (pitchers). Total bases divided by at-bats.

Strikeouts. For pitchers, batters struck out, for batters, times struck out.

Percentage of plate appearances that result in a strikeout.

Number of strikes seen (batter) or thrown (pitcher)

True Average incorporates aspects that other linear weights-based metrics ignore. Reaching base on an error and situational hitting are included; meanwhile, strikeouts and bunts are treated as slightly more and less damaging outs than normal. The baseline for an average player is not meant to portray what a typical player has done, but rather what a typical player would do if given similar opportunities. That means adjustments made for parks and league quality. True Average's adjustments go beyond applying a blanket modifier-players who play more home games than road games will see that reflected in their adjustments. Unlike its predecessor, Equivalent Average, True Average does not consider baserunning or basestealing.

Here is an example of the True Average spectrum based upon the 2009-2011 seasons:

Excellent - Miguel Cabrera .342
Great - Alex Rodriguez .300
Average - Austin Jackson .260
Poor - Ronny Cedeno .228
Horrendous - Brandon Wood .192
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See: http://www.baseballprospectus.com/article.php?articleid=11717

0.9 (from the article) is no longer a stationary number, but a scale based on current season runs. It's all the way up to almost 1.07 now, due to run scoring being so much lower than when Colin wrote this (from the link above):

From 1993 to 2009, you can figure TAv simply as:

0.260 + (RAA/PA)*.9

Now, we will be tuning those values slightly to match the batting average for that season, but other than
that, that’s the formula for TAv we will be using once the new stat reports are rolled out.

[...]

All that matters essentially is the computation of the initial R/PA values. When people ask about wOBA, most
of the time what they really care about is the values presented on Fangraphs, derived from this set of
linear weights developed by Tom Tango.

Total bases - A home run is 4 total bases, a triple is 3, a double is 2, and a single is 1. Walks, steals, sacrifices, and other non-hit advancement do not count as a total base.

Total Base Percentage -- total bases per plate appearance (as opposed to slugging average, SLG, which is total bases per at-bat)

Times On Base -- times reaching base by hit, walk, or hit by pitch. Reaching by error is sometimes included, depending on the context.

Hits plus doubles plus two times triples plus three times home runs.

The total number of baserunners that have been on base for a batter's plate appearances.

Unintentional bases on balls (walks)

Unintentional base on balls rate (UBB per plate appearance).

Unintentional Walk Rate (BB) is one of five primary production metrics used by PECOTA in identifying a player's comparables. It is defined as (BB-IBB)/PA.

Value Over Replacement Player. The number of runs contributed beyond what a replacement-level player at the same position would contribute if given the same percentage of team plate appearances. VORP scores do not consider the quality of a player's defense.

Here is an example of the Value Over Replacement Player spectrum based on the 2011 season:

Excellent - Matt Kemp 95.2
Great - Robinson Cano 51.4
Average - Eric Hosmer 19.9
Poor - Derrek Lee 3.2
Horrendous - Adam Dunn -22.6

VORP for position players consists of batting runs above average (BRAA), position adjustment (POS_ADJ), baserunning runs above average (BRR - which includes - but is not limited to - stolen bases and times caught stealing ), and an adjustment for replacement level (REP_ADJ).

Perhaps no sabermetric theory is more abstract than that of the replacement-level player. Essentially, replacement-level players are of a caliber so low that they are always available in the minor leagues because the players are well below major-league average. Prospectus' definition of replacement level contends that a team full of such players would win a little over 50 games. This is a notable increase in replacement level from previous editions of Wins Above Replacement Player.

Here is an example of the Wins Above Replacement Player spectrum based on the 2011 season:

Excellent - Jose Bautista 10.3
Great - Hunter Pence 5.2
Average -Gaby Sanchez 2.0
Poor - Adam Lind 0.5
Horrendous - Adam Dunn -1.7

WARP components can be found in this article, which also describes 2015 changes to FRAA: http://www.baseballprospectus.com/article.php?articleid=27944

Zone Rate is calculated using PITCHf/x data and shows the percentage of pitches seen (by hitters) or thrown (by pitchers) that are in the rule-book strike zone.

Hitter Examples (2012):

Very few: Pablo Sandoval, 0.4005
Few: Kirk Nieuwenhuis, 0.4833
Around average: Andres Torres, 0.5054
Many: Bobby Abreu, 0.5244
Very many: Chone Figgins, 0.5787

Pitcher Examples (2012):

Very few: Jared Hughes, 0.33554
Few: Jared Burton, 0.4775
Around average: Jeremy Accardo, 0.4879
Many: Joe Blanton, 0.5217
Very many: Jake Mcgee, 0.5897