Table 1.
Rate Statistics in MLB Pitching a
| Statistic | Definition |
|---|---|
| Earned run average (ERA) | Average number of earned runs a pitcher allows divided by 9 innings |
| Adjusted ERA (ERA+) | ERA adjusted to the player’s ballpark |
| Walks and hits per inning (WHIP) | Total of walks and hits divided by innings |
| Strikeouts per 9 innings (K/9) or strikeout percentage (K%) | A pitcher’s strikeout rate per 9 innings or, alternatively, the percentage of total batters that are struck out |
| Walks per 9 innings (BB/9) or walk percentage (BB%) | A pitcher’s walk rate per 9 innings or, alternatively, the percentage of total batters that are walked |
| Strikeout-to-walk rate (K/BB) | A pitcher’s ratio of strikeouts to walks |
| Opponent batting average (BA) | Hits per at-bats by the opposing hitters |
| Wins above replacement (WAR) | A single number that presents the number of wins the player added above what a replacement player would add |
| Home runs per 9 innings (HR/9) | Home runs allowed by a pitcher per 9 innings |
| Fielding independent pitching (FIP) | Measures a pitcher’s effectiveness at preventing HR, BB, and hit by pitch and causing K; the average FIP is set as the same as the average MLB ERA |
a All definitions are from http://www.baseballreference.com or http://www.mlb.com/stats/pitching. MLB, Major League Baseball.