📊 Baseball Stats Glossary
Every number you’ll meet on a game page or in a briefing, explained in plain language.
The line score basics: R, H, E
At the right edge of every line score you’ll find three columns: R (runs), H (hits), and E (errors). Lots of hits but few runs means chances went begging; multiple errors suggest some runs were the defense’s fault. Three numbers already tell you the shape of a game.
Hitting stats
| Stat | What it means |
|---|---|
| Batting average (AVG) | Hits ÷ at-bats. The classic yardstick, but it ignores walks. .300 is elite. |
| On-base percentage (OBP) | How often a batter reaches base without making an out — a better read on offensive value than AVG. |
| Slugging (SLG) | Total bases ÷ at-bats, weighting doubles and homers — the "quality" of hits. |
| OPS | OBP + SLG. If you look at one number, make it this: roughly .700 is average, .800 is good, .900+ is elite. |
| HR / RBI | Home runs / runs batted in. RBI also depends on teammates getting on base ahead of you. |
| BB / SO | Walks and strikeouts — the plate-discipline stats. High walks with low strikeouts means a batter who’s hard to put away. |
| Stolen bases (SB) | Bases stolen. Rule of thumb: attempts only help the team at roughly a 70%+ success rate. |
Pitching stats
| Stat | What it means |
|---|---|
| ERA | (Earned runs × 9) ÷ innings pitched — runs allowed per nine innings by the pitcher’s own doing. For a starter, low 3s is solid and the 2s are ace territory. |
| WHIP | (Hits + walks) ÷ innings: baserunners allowed per inning. Under 1.20 is strong; under 1.00 is dominant. |
| Innings pitched (IP) | The decimal counts outs, not tenths: 5.1 IP = 5 innings plus one out; 5.2 = plus two outs. |
| Strikeouts (SO, K/9) | K/9 converts strikeouts to a per-nine-innings rate — the go-to proxy for pure stuff. |
| Quality start (QS) | Six-plus innings with three or fewer earned runs — a consistency measure for rotations. |
| W / L / SV / HLD | Wins and losses lean heavily on run support, so treat them lightly. Saves belong to closers, holds to setup men. |
Phrases you’ll see on game pages
- Probable starter: the announced starting pitcher. KBO probables are named the day before and can still change with weather or roster moves.
- Confirmed lineup: the batting order and positions, posted about an hour before first pitch — where you learn whether a key player sits.
- Bullpen / consecutive appearances: the relief corps, and whether the same arms have pitched several days running. A worn bullpen loses effectiveness.
- Head-to-head (H2H): the season series between the two clubs (or a pitcher vs. a lineup). Small samples — treat as context, not destiny.
- Park factor: whether a ballpark favors hitters or pitchers. Deep outfields like Jamsil suppress home runs.
- Last 10: the team’s short-term form. Read it alongside the full-season record, not instead of it.
AIGround briefings cite exactly these stats as evidence. If the numbers feel foreign, keep this page open while you read — and remember every prediction is for information and entertainment only, never betting advice.