Stat Glossary

Batting

G Games Games in which the player appeared.
PA Plate Appearances Trips to the plate — the denominator for most modern rate stats. Includes walks, sacrifices, and times hit by pitch, unlike at-bats. ~600–700 for a full-season regular
AB At Bats Plate appearances excluding walks, hit-by-pitches, sacrifices, and catcher's interference.
R Runs Runs scored. 100+ is an excellent season
H Hits Total hits. 200 hits is a historically notable season
2B Doubles Two-base hits. 40+ leads most seasons
3B Triples Three-base hits — mostly a speed stat. 10+ leads the league most years
HR Home Runs Home runs. 30+ is a power season; 40+ is elite
RBI Runs Batted In Runs driven in. Heavily dependent on teammates reaching base ahead of the batter — descriptive, not predictive. 100+ traditionally notable
SB Stolen Bases Stolen bases. 30+ marks an elite runner
CS Caught Stealing Times thrown out attempting to steal. Break-even success rate is roughly 75% — below that, running costs runs.
BB Walks Bases on balls.
IBB Intentional Walks Intentional walks — largely a measure of how much the opponent fears the hitter.
SO Strikeouts Times struck out.
HBP Hit By Pitch Times hit by a pitch — reaches base, counts toward OBP.
SF Sacrifice Flies Fly outs that scored a runner. Not charged as an at-bat.
SH Sacrifice Bunts Sacrifice bunts.
GDP Grounded Into Double Play Double plays grounded into.
BB% Walk Rate Walks per plate appearance. A plate-discipline skill that stabilizes quickly and translates across levels. BB ÷ PA league avg ~8.5%; 12%+ excellent; <5% poor
K% Strikeout Rate Strikeouts per plate appearance. Lower is better for hitters. SO ÷ PA league avg ~22%; <15% elite contact; >30% concerning
AVG Batting Average Hits per at-bat. The classic rate stat, but it ignores walks and treats all hits equally — use OBP/SLG/wOBA for a fuller picture. H ÷ AB league avg ~.245; .300+ excellent
OBP On-Base Percentage How often the batter reaches base per plate appearance. The single most important traditional rate stat — outs are the game's scarcest resource. (H + BB + HBP) ÷ (AB + BB + HBP + SF) league avg ~.315; .380+ elite
SLG Slugging Percentage Total bases per at-bat — batting average weighted by hit type. (1B + 2×2B + 3×3B + 4×HR) ÷ AB league avg ~.400; .550+ elite
OPS On-Base Plus Slugging OBP plus SLG. A quick-and-dirty overall offense number; wOBA weighs the components more accurately. OBP + SLG league avg ~.715; .900+ elite
ISO Isolated Power Extra bases per at-bat — raw power stripped of singles. SLG − AVG league avg ~.155; .250+ elite power
BABIP Batting Average on Balls In Play Batting average on balls put in play (excludes HR and SO). For hitters it partly reflects speed and contact quality, but big swings from a player's career norm usually signal luck that will regress. (H − HR) ÷ (AB − SO − HR + SF) league avg ~.295
wOBA Weighted On-Base Average OBP's smarter sibling: every way of reaching base is weighted by its actual run value (a walk is worth less than a double, which is worth less than a homer). The best single rate stat for offense. Imported, not computed here. linear-weighted value of BB, HBP, 1B, 2B, 3B, HR per PA league avg ~.320; .400+ elite
xwOBA Expected wOBA Statcast's estimate of what a hitter's wOBA *should* be, based on exit velocity, launch angle, and (for some events) sprint speed. Big gaps between wOBA and xwOBA often predict regression. compare to wOBA: higher xwOBA suggests bad luck so far
xBA Expected Batting Average Statcast's estimate of batting average from quality of contact rather than outcomes.
xSLG Expected Slugging Statcast's estimate of slugging percentage from quality of contact.
wRC+ Weighted Runs Created Plus Total offense on an index scale: 100 is exactly league average, and every point above is one percent better than average — park- and league-adjusted, so eras and ballparks compare cleanly. Imported, not computed here. 100 = average; 140+ elite; 160+ MVP-caliber
WAR Wins Above Replacement Total player value — hitting, baserunning, defense, position — expressed as wins added versus a replacement-level player. Imported from the source that computes it; methodologies differ between sites. 2+ solid starter; 4+ All-Star; 6+ MVP-caliber

Pitching

W Wins Pitcher wins. Team- and luck-dependent; kept for familiarity, not analysis.
L Losses Pitcher losses.
SV Saves Games saved. 30+ marks a full-time closer
HLD Holds Holds — a setup reliever's save-equivalent.
BS Blown Saves Save opportunities lost.
G Games Appearances.
GS Games Started Starts. 30+ is a full starter season
CG Complete Games Complete games — increasingly rare.
SHO Shutouts Complete-game shutouts.
IP Innings Pitched Innings pitched, shown in the conventional .1/.2 thirds notation. Stored internally as outs so career totals sum exactly. 180+ IP is a durable starter season
TBF Total Batters Faced Batters faced — the pitcher's plate-appearance denominator for K% and BB%.
H Hits Allowed Hits allowed.
R Runs Allowed All runs allowed, earned or not.
ER Earned Runs Earned runs allowed.
HR Home Runs Allowed Home runs allowed.
BB Walks Allowed Walks issued.
IBB Intentional Walks Issued Intentional walks issued.
SO Strikeouts Batters struck out. 200+ over a season is elite for a starter
HBP Hit Batters Batters hit by pitch.
WP Wild Pitches Wild pitches.
BK Balks Balks.
K/9 Strikeouts per 9 Innings Strikeout rate per nine innings. K% (per batter faced) is slightly more accurate; K/9 remains the familiar form. SO × 9 ÷ IP league avg ~8.5; 10+ excellent
BB/9 Walks per 9 Innings Walk rate per nine innings. BB × 9 ÷ IP league avg ~3.2; under 2.0 elite control
HR/9 Home Runs per 9 Innings Home runs allowed per nine innings. HR × 9 ÷ IP league avg ~1.2
K% Strikeout Rate Strikeouts per batter faced — the more precise strikeout rate. SO ÷ TBF league avg ~22%; 28%+ elite
BB% Walk Rate Walks per batter faced. BB ÷ TBF league avg ~8%; under 6% excellent
WHIP Walks + Hits per Inning Baserunners allowed per inning. (BB + H) ÷ IP league avg ~1.30; under 1.10 excellent
AVG Batting Average Against Opponents' batting average. league avg ~.245
ERA Earned Run Average Earned runs allowed per nine innings. The classic pitching stat — real outcomes, but noisy: defense and sequencing luck are baked in. Read it next to FIP. ER × 9 ÷ IP league avg ~4.20; under 3.00 elite
FIP Fielding Independent Pitching What a pitcher's ERA would look like based only on what he controls — strikeouts, walks, hit batters, and home runs — with league-average results on balls in play. On the ERA scale. A pitcher whose ERA is far below his FIP is often getting defense/luck help. (13×HR + 3×(BB+HBP) − 2×SO) ÷ IP + constant league avg ~4.20; under 3.30 elite
xFIP Expected FIP FIP with the home-run component replaced by a league-average HR-per-fly-ball rate — useful because HR/FB is largely luck for most pitchers. Imported where available.
WAR Wins Above Replacement Total pitcher value versus a replacement-level arm, in wins. Imported from the source that computes it. 2+ solid starter; 4+ All-Star; 6+ Cy Young-caliber