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        Glossary of Terms

   This glossary contains definitions of statistical terms and measures that may be new to the average baseball fan and the advanced fan alike.  The sources of many of the terms are Total Baseball and Stats, Inc., two of the premier stats services.

ADJUSTED Generally denotes a statistic that has been altered to reflect normalization to a league average or home park factor.  Stats that are normalized include Batting Average, Batting Runs, Runs Created, On Base Percentage, Slugging Average, Earned Run Average, OPS and Pitcher Runs.

ASSIST Credited to a player who throws out an opposing runner.  Credited to pitchers on strikeouts in some of baseball's early years.

ASSIST AVERAGE Assists divided by games played. Stat created by Philadelphia baseball writer Al Wright in 1875.

AT-BATS Charged to a batter when he engages in a plate appearance, except for when the batter's appearance results in a base on balls or a sacrifice. Charged on sacrifice hits, 1889-1893; on sacrifice-fly situations, 1931-1938 and 1940-1953; bases on balls, 1876, 1887.

AVERAGE AND OVER Early form of expressing averages for base hits, runs, and outs. The average of a batter with 23 hits in six games would be not 3.83 but 35 (an average of 3 with an overage, or remainder, of 5); borrowed from cricket.

BASES ON BALLS Counted when a batter takes four balls in a single at-bat and is awarded first base. Counted as outs for batters in 1876 and as hits for batters in 1887; awarded for a varying number of errant pitches since 1876, from nine in that year to the current four (standardized in 1889). (After 1887, the batter was no longer allowed to specify strike zone as waist to shoulders or waist to shins.)

BASES ON BALLS PERCENTAGE Batters' stat - walks per 100 at-bats plus bases on balls.

BASES ON BALLS PER GAME Game defined as nine innings; league- leading pitchers calculated on basis of lowest mark; computed as bases on balls times nine, divided by innings.

BATTER'S PARK FACTOR The Park Factor shown in the batters' section of the team statistics in the Annual Record, Player Register, and Home-Road Statistics. Above 100 means batters benefited from playing half their games in a good hitting park. Abbreviated as BPF or, in what are clearly batters' stats (as in the Player Register) simply as PF. See entry for Park Factor for the computation.

BATTERY ERRORS In baseball's early years, wild pitches, passed balls, and hit batsmen were lumped together in the statistical summary of a game as battery errors and were charged against the fielding percentage of the pitcher or catcher.

BATTING AVERAGE Calculated as base hits divided by at-bats ever since its first appearance in print in 1874.  In 1876 walks were counted as at-bats, and in 1887 they were counted as at-bats and as hits.

BATTING RUNS The Linear Weights measure for how many runs a hitter contributes above and beyond what a league average replacement player would provide.  Converts a number of offensive statistics into their run equivalent, based on Pete Palmer's 1978 computer simulation of major league games since 1901.  The formula is:

Runs = (.47) 1B + (.78) 2B + 1.09 (3B) + (1.40) HR + .33 (BB+HBP)

          - .25 (AB-H) - (0.50) (Outs on base)

 

BATTING WINS Adjusted Batting Runs divided by the number of runs required to create an additional win beyond average.  That average is defined as a team record of .500 because a league won-lost average must be .500.  Abbreviated as BW.  See Runs Per Win.

DIFFERENTIAL A Total Baseball measure. The difference between a team's actual won-lost record and that predicted by the total of its Pitching Wins, Batting Wins, Fielding Wins, and Stolen Base Wins; this measure indicates the extent to which a team outperformed or underperformed its talent.  Abbreviated as DIF.

EARNED RUN AVERAGE Calculated as earned runs times nine, divided by innings pitched. For a few years after being introduced as an official stat in the National League in 1912 and the American League in 1913, runs aided by stolen bases were not counted as earned.  For years before 1912, ERA has been constructed from raw data, but for some teams in some seasons, earned runs cannot be identified with perfect certainty.

ERA+ (Adjusted ERA) ERA normalized to the league average - which is done by dividing the league average ERA by the individual ERA - and then factoring in home park effect.

EXPECTED WINS Calculated for the team based on its actual runs scored and allowed, not its predicted runs scored and allowed.  A team that allows exactly as many runs as it scores is predicted to play .500 ball.  The equation for expected wins is:

  
(Runs Scored - Runs Allowed)        (Wins + Losses)  
--------------------------    +    ------------------   
   Runs Per Win                             2                       

Abbreviated as W-EXP.

FIELDING AVERAGE Defined as putouts and assists divided by the total of putouts, assists, and errors. The weakness of this stat is that it values a player with minimal range but good hands over another player who may accept many more chances but mishandle a few of these.  Abbreviated as FA.  See Range Factor, Total Chances.

FIELDING RUNS The Linear Weights measure of runs saved beyond what a league-average player at that position might have saved, defined as zero; this stat is calculated to take account of the particular demands of the different positions.

For second basemen, shortstops, and third basemen, the formula begins by calculating the league average for the position:

  
     pos        .20 (PO + 2A - E + DP) league at position        
AVG        =   ---------------------------------------  
     lg                 (PO league total - K league total)    
where A = assists, PO =putouts, E = errors, DP = double plays, and K =strikeouts. Then Total Baseball estimate the number of innings for each player at each position based upon each player's entire fielding record and his number of plate appearances.

Assists are doubly weighted because more fielding skill is generally required to get one than to record a putout.

For catchers, the above formula is modified by removing strikeouts from their formulas and subtracting not only errors but also passed balls divided by two. Also incorporated in the catcher's Fielding Runs is one tenth of the adjusted Pitching Runs for the team, times the percentage of games behind the plate by that catcher.

For pitchers, the above formula is modified to subtract individual pitcher strikeouts from the total number of potential outs (otherwise, exceptional strikeout pitchers like Nolan Ryan or Bob Feller would see their Fielding Runs artificially depressed). Also, pitchers' chances are weighted less than infielders' assists because a pitcher's style may produce fewer ground balls. Thus the formula for pitchers is .10(PO + 2A - E + DP), whereas for second basemen, shortstops, and third basemen it is .20(PO + 2A - E + DP).

For first basemen, because putouts and double plays require so little skill in all but the odd case, these plays are eliminated, leaving only .20(2A E) in the numerator.

For outfielders, the formula becomes .20(PO + 4A - E + 2DP).  The weighting for assists is boosted here because a good outfielder can prevent runs through the threat of assists that are never made; for them, unlike infielders, the assist is essentially an elective play, like the stolen base.  Outfielders' Fielding Runs were subject to some degree of error because outfielders sometimes switch fields within a game or season (Babe Ruth, for example, was positioned in the field that required the lesser range--right field in Yankee Stadium, left field in most road parks).  Also, short distances to left-or right-field walls in some parks tend to depress putout totals.

Since the third edition of Total Baseball, however, researchers there have obtained breakouts of all outfielders' games in left, center, and right fields.  Center fielders now have higher ratings than they did in the first and second editions.  Abbreviated as FR.

Example: Ozzie Smith in 1978.

Begin by looking at the league average - NL shortstops in 1978, had 3,191 PO, 6,199 A, 332 E, and 1,105 DP.  The league as a whole had 52,000 PO and 9905 K. The AVG(POS,LG) is therefore 

.20*(3191+2*6199-332+1105)/(52000-9905) = 0.0777

The Wiz in '78 played 1,327 of the 1,433 2/3 innings played by the Padres (0.926 of the total).  Ozzie had 264 PO, 548 A, 25 E, and 98 DP.  The Padres had 4,301 putouts as a team and fanned 744 hitters.  Ozzie's FR are:

.20*(264+2*548-25+98)-((4301-744)*.0777*.926) = 31

FIELDING WINS Fielding Runs divided by the number of runs required to create an additional win beyond average.  That average is defined as a team record of .500 because a league won-lost average must be .500.  Abbreviated as FW.  See Runs Per Win.

GAMES BEHIND Figured by adding the difference in wins between a trailing team and the leader to the difference in losses, and dividing by two. Thus a team that is three games behind may trail by three in the win column and three in the loss column, or four and two, or any other combination of wins and losses totaling six. Abbreviated as GB.

GAME-WINNING RUN BATTED IN Credited to the batter who drives in a run that gives his club a lead that it never relinquishes, no matter when that run is driven in nor what the final score is. Introduced in 1980 as an official stat and later disowned, the GWRBI is not recorded in this volume.

GROUNDED INTO DOUBLE PLAY Kept officially since 1993 in the NL and 1939 in the AL (though the NL data of 1933-38 made no distinction between lined-into double plays and grounded-into double plays, and the AL data of 1939 was not published). This stat tends to be overvalued by the general public as an indicator of rally-killing ineptitude. Instead, it is largely a function of high totals of at-bats, which tend to be accumulated by the game's best players, not its worst. Abbreviated as GIDP.

HANDS OUT The original 1840s scoring term for batters producing outs either at the plate or on the bases. On a force out, the runner retired on the bases would be charged with a hand out, not the batter. Also called Hands Lost, and abbreviated as HO or HL.

HIT BY PITCH A batter struck by a pitched ball was not awarded first base until 1884 in the American Association and 1887 in the National League. Reconstruction of stats for batters and pitchers in the years 1897-1908 has been accomplished. Abbreviated as HBP.

HITS Bases on balls originally counted as hits in 1887, but are recorded in this volume as neither hits nor at-bats.

HOME RUN FACTOR A measure of the home runs hit in a given ballpark, with 100 representing the average home park and the highest figure above that representing the best home-run park. Computed in the same manner as Home Run Batter Rating (see above). Abbreviated as HRF.

HOME RUN PERCENTAGE Home runs per 100 at-bats.

HOME RUN PITCHER RATING A measure of a team's ability to prevent home runs, taking into account the Home Run Factor (see above) of the park and the team's not having to face its own batters. The average mark is represented as 100, and the lowest figure beneath that indicates the best.

HOME RUNS When is a home run not a home run?  Before 1920, not if it came with men on base in the ultimate inning and created a margin of victory greater than one run.  A ruling of the Special Baseball Records Committee in 1969 reversed its earlier decision that had made home runs of 37 disputed final-inning, game-winning base hits.  In accordance with the practice of the day, such a hit, even if it sailed out of the park, would be credited with only as many bases as necessary to plate the winning run.  Thus Babe Ruth's "715th home run," hit on July 8, 1918, to win a game against Cleveland, remained a triple, and Jimmy Collins and Sherry Magee were each deprived of two home runs.

INNINGS PITCHED Official baseball practice was, until 1982, to round off fractional innings for individuals to the next highest inning. Since then fractional innings have been kept for individuals and teams. In this volume fractional innings are supplied for all individuals and all teams in all years. Those men who took a turn on the mound but failed to retire a batter are credited with no innings pitched and, if they allowed a runner or runners to score, an ERA of infinity.

INTENTIONAL BASES ON BALLS Recorded only since 1955.

ISOLATED POWER Total bases minus hits, divided by at-bats; in other words, Slugging Average minus Batting Average. Appears to have been created by Allan Roth and Branch Rickey in the 1950s.

LEAGUE-AVERAGE REPLACEMENT PLAYER That model player who performs at precisely the league average, creating a baseline against which to measure others.

ON BASE PERCENTAGE Created by Roth and Rickey in its current form - hits plus walks plus hit by pitch, divided by at-bats plus walks plus hit by pitch - in the early 1950s, although there were nineteenth-century forebears such as "Reached First Base." When OBP, as it is abbreviated, was adopted as an official stat in 1984, the denominator was expanded to include sacrifice flies. The effect is to penalize a batter in his on base percentage by giving him a plate appearance while at the same time crediting him in his batting average by deleting the plate appearance. In this book we calculate OBP without considering sacrifice flies, which in any event are calculable on a continuing basis only since 1954.

ON BASE PLUS SLUGGING A simple but elegant measure of batting prowess, in that the weaknesses of one-half of the formulation, On Base Percentage, are countered by the strengths of the other, Slugging Average, and vice versa. 

When adjusted for home park and normalized to league average, the calculation is modified slightly to create a baseline of 100 for a league-average performance. For PRO+, the calculation is

    Player On Base Pct.    Player Slugging Avg.   
    -------------------- + -------------------- - 1  
    League On Base Pct.   League Slugging Avg. 
This produces a figure with a decimal point - an above-average figure, like 1.46, or a below-average figure, like 0.82.

     Often abbreviated as OPS, though it is abbreviated by Total Baseball as PRO, and abbreviated as PRO+ when normalized to a league average and adjusted for Park Factor.

OPPONENTS' BATTING AVERAGE Hits allowed divided by at-bats allowed (or, if at-bats allowed is unknown, then at-bats equals hits plus inning times "K," where "K" is the league average of at-bats minus hits, all over innings). Abbreviated by Total Baseball as OAV.

OPPONENTS' ON BASE PERCENTAGE For years before 1908 in the American League and 1903 in the National League, the number of batters facing a pitcher has been constructed from the available raw data. We have subtracted league base hits from league at-bats, divided by league innings pitched, multiplied by the pitcher's innings, and added his hits and walks allowed and hit by pitch and sacrifices, if available.  Abbreviated by Total Baseball as OOB.

OUTS Until 1883, included catching a ball on one bounce in foul ground. Not credited after three strikes in 1887, when the rule was "four strikes and yer out" - as it was, in fact, from 1871-1881, when batters commonly received "warning pitches" rather than called strikes.

OUTS PER GAME The 1860s successor to Hands Out (see above), it joined with Runs Per Game to form the batting record before the rise of professional league play.

PARK FACTOR Calculated separately for batters and pitchers.  Above 100 signifies a park favorable to hitters; below 100 signifies a park favorable to pitchers.

   STATS uses a five-year average Park Factor for players and teams unless they change home parks. They first compute a Park Index, which is the ratio of runs scored (both by and against a particular team) in the home ballpark to the runs scored (by and against) in visiting ballparks.

   Once an index has been created, adjustments are made to reflect the fact that a team plays fewer innings at home than on the road - the home team doesn't bat in the bottom of the ninth if it is leading - and to reflect the fact that the team being rated doesn't get to play road games in its own park. For example, the Colorado Rockies play in Coors Field, a ballpark which boosts run production. Their Park Index is going to be very high, because far more runs are scored at home than on the road. However, every other team in the league gets to play some road games at Coors, benefiting from it's friendliness to hitters; the Rockies must play every road game away from Coors, and that dilutes their Park Factor.

PITCHER RUNS A Total Baseball measure devised to quantify how many runs a pitcher saves for his team relative to a league average pitcher. The formula is:

                    (league ERA - pitcher's ERA) x (innings pitched by pitcher)
Pitcher Runs =                                         ------------------------------
                                                                                9

In this manner, the value of a pitcher in terms of runs prevented can be measured.

PUTOUT AVERAGE Putouts divided by games played; a stat created by Philadelphia baseball writer Al Wright in 1875.

QUALITY START A game started in which a pitcher lasts for six innings or more and allows three runs or less.

RATIO Hits plus walks plus hit batsmen allowed per nine innings. Abbreviated as RAT.

RUN BATTED IN Though widely regarded as a good measure of a batter's overall productivity and value to his team, the RBI is extremely situation-dependent, denying equal access to opportunity on the basis of a player's team, slot in the batting order, and particularly the men surrounding him in the batting order.

RANGE FACTOR A measure of defense - the average number of defensives plays a player makes in a nine-inning game.  Comparing this to the league range factor gives you an idea of how a defensive replacement would fare.

RUNS CREATED Bill James's formulation for run contribution from a variety of batting and baserunning events.  Many different formulas are used, depending upon data available.  In its basic expression, the formula is:

         (Hits + Walks) (Total Bases)  
        --------------------------  
             At-Bats + Walks 


   The essence of this formulation is that the ability to get on base and the ability to push baserunners around fairly describes offensive ability. James later refined the formula with a "stolen base version":

 

(Hits+Walks-Caught Stealing)(Total Bases +.55 X Stolen Bases)  
----------------------------------------------------------  
                  At-Bats + Walks

 

     In it's current version, the formula is:

 

A factor: Hits + Walks + HBP - GIDP - CS

B factor: Total Bases + ((Walks + HBP - Intentional Walks) * .24) + (SB * .62)

               + ((SH + SF) * 0.5) - (SO * .03)

C factor: AB + Walks + HBP +SH + SF


    Runs Created = (A + B) / C

RUN FACTOR A measure of the run scoring in a given ballpark compared to other ballparks, with 100 representing the average home park and the highest figure above that representing the best hitters' park. Abbreviated as RF, it is computed on the basis of comparing runs scored and allowed per inning at home and on the road. Innings are estimated from the number of games and games won, allowing for the home team not batting in the final inning of a game in which it leads. The resulting Run Factor is then compared to the league average.

RUNS PER WIN A measure of how many additional runs it takes to create an additional win.  Although the number varies from year to year, Pete Palmer has devised a rule of thumb that states: for each additional ten runs scored, one win results.  More specifically, wins are increased in proportion to the square root of runs scored - so runs-per-win is roughly the square root of the number of runs scored per game.  Thus, the 10:1 Palmer rule of thumb is fine as long as the runs scored in a game are around 10.

RBI OPPORTUNITIES An official American League stat for the first three weeks of 1918, until the league saw how much work it involved and scrapped it. Still a good idea, sort of, and the folks at the Elias Sports Bureau have tracked this type of "situational stat" since 1975.

RELATIVE BATTING AVERAGE Pioneered by David Shoebotham in a Baseball Research Journal article in 1976, this was the first traditional stat normalized to league average so as to permit cross-era comparison.  Most folks who have employed this measure simply divide individual batting average by league batting average.  Shoebotham's original computation was more precise:

           player's hits / player's AB  
RBA = ---------------------------------------  
           (league hits - player's hits) /  (league AB - player's AB)

In this manner a player's own performance would not be compared with itself.

SACRIFICE FLY First recognized as an event in 1908 but indistinguishable in the official records from sacrifice hits until 1954. There has been much flip-flopping since 1930 on whether to credit the sacrifice flier with an at-bat or an RBI or whether a fly ball that advances a runner to a base other than home plate also should exempt a man from an at-bat.

SACRIFICE HITS Invented in the 1860s, recorded since 1889; sacrificer charged with an at-bat until 1894. Sabermetricians frown on the strategy because all the studies show that the trading of an out for a base advanced is a losing strategy - lowering the run expectations of the team that attempts it - in all but the most unusual of cases ... even if the sacrifice "succeeds."

SACRIFICE HITS ALLOWED Computed officially in the National League since 1913 but not published until 1916, and kept in the American League since 1921 but not published until 1922; what it signified about anything is unclear.

SAVE Created by Jerome Holtzman of the Chicago Sun-Times, the save began to be reported by The Sporting News on a regular basis in 1960. The major leagues adopted the save in 1969, at which time it was credited to a reliever who finished a game that his team won. In 1973 the save was redefined so that a reliever had not only to finish the game but also to find the potential tying or winning run on base or at the plate, or, alternately, to pitch the final three innings of a victorious contest. In 1975 the rule was liberalized to include a reliever's appearance of one inning or more in which he protects a lead of three runs or less; or he enters the game with the tying or winning run on base, at bat, or on deck; or he pitches three innings to the game's conclusion.

SHUTOUTS On an individual basis, credited only to pitchers of complete-game scoreless victories; former practice was to credit combined shutouts to the starting pitcher if he had pitched most of the way. Abbreviated as SH.

SITUATIONAL STATISTICS How does a batter perform with the bases loaded? At night? On artificial turf? With no one on base? After the seventh inning when his team is tied or trails? The specialty of Baseball Workshop, Stats, Inc., and the Elias Sports Bureau.

SLUGGING AVERAGE Total bases divided by at-bats; combines nicely with On Base Percentage to create a simple but elegant measure of performance. Usually abbreviated as SLG.

STARTER RUNS Identical to Pitching Runs but confined to starting pitchers, defined as those who average more than three innings per appearance. Abbreviated by Total Baseball as SR.

STOLEN BASE AVERAGE Stolen bases divided by attempts; its computation is dependent upon the availability of caught-stealing numbers. Abbreviated by Total Baseball as SBA.

STOLEN BASE RUNS For teams, the Linear Weights measure of runs contributed beyond what a league-average basestealing team might have gained, defined as zero; for individuals, Stolen Base Runs are calculated on the basis of the 66.7 percent success rate that sabermetric studies have shown to be the break-even point for producing runs beyond the average.  Availability dependent upon caught stealing data as with Stolen Base Average.  The formula is simple:

.30(Stolen Bases) - .60(Caught Stealing). 

A man who steals two bases in three attempts is merely spinning his wheels in terms of value to his team, and even a man who succeeds at an 80 percent clip will have to steal a lot of bases - about 65 - to create just one win beyond average.  Abbreviated by Total Baseball as SBR.

STOLEN BASE WINS Stolen Base Runs divided by the number of runs required to create an additional win beyond average.  Those runs are generally around around 10 - historically in the range of 9-11.  Abbreviated as SBW.  See Runs Per Win.

STOLEN BASES Credited to a player who moves from one base to the next without the benefit of the player at bat making contact with the baseball.  Recorded since 1886, but until 1898 steals are thought to have included a variety of daring baserunning exploits, such as going from first to third on a single or advancing an extra base on an out.  Abbreviated as SB.

STRIKEOUTS Credited to a pitcher who makes an out on strikes. Varying rules concerning the strike zone, the foul strike, and the warning pitch - not to mention the fourth strike of 1887 - all contribute to making the cross-era comparison of strikeout accomplishments a very sticky business.  Abbreviated as SO.

STRIKEOUT PERCENTAGE A batters' stat: fewest strikeouts per 100 at bats.

TOTAL AVERAGE Tom Boswell's formulation for offensive contribution from a variety of batting and baserunning events. The concept of the numerator is bases gained, that of the denominator is outs made:

(Total Bases + Steals + Walks + HBP - Caught Stealing)  
-----------------------------------------------------  
(At-Bats - Hits + Caught Stealing + GIDP)

Abbreviated as TA. See Base-Out Percentage.

TOTAL BASEBALL RANKING The "MVP" of statistics, this ranks pitchers and position players by their total wins contributed in all their endeavors, revealing the most valuable performers in a given year.  Abbreviated as TBR, it is not a computed stat but a sorting of players and pitchers by, respectively, the sum of their Total Batter Rating and Total Pitcher Index.

TOTAL BASES AVERAGE Henry Chadwick's measure that divided total bases by games played; a forerunner of the Slugging Average.

TOTAL BASES RUN A silly stat of one year's duration, 1880, this was sort of an RBI in reverse, from the runner's perspective. Also called "Bases Touched," it was nothing more than that and signified nothing about individual talent. Trivia: the National League's leader in 1880 was Abner Dalrymple, with 501 bases touched.

TOTAL CHANCES Putouts plus assists plus errors; in other words, total chances offered, not total chances accepted.

TOTAL PITCHER INDEX The sum of a pitcher's Pitching Runs - expressed as Ranking Runs, employing the same formula used to compute Relief Ranking Runs - Batting Runs (in the AL since 1973, zero), and Fielding Runs, all divided by the Runs Per Win factor for that year (generally around 10, historically in the 911 range); abbreviated as TPI.  See Runs Per Win, Relief Ranking.

TOTAL PLAYER RATING The sum of a player's Adjusted Batting Runs, Fielding Runs, and Base Stealing Runs, minus his positional adjustment, all divided by the Runs Per Win factor for that year (generally around 10, historically in the 9-11 range). See Runs Per Win.

TRIPLE CROWN Long regarded as consisting of batting average, home runs, and RBI, but was not always so.  In the early years of this century, newspapers spoke of Ty Cobb shooting for the "triple crown" of batting average, runs, and hits.

WIN Credited to a pitcher who is on the mound when his team scores the winning run.

WON-LOST PERCENTAGE Computed as wins over decisions.


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