Essential metrics for evaluating pitcher performance
The average number of earned runs a pitcher allows per nine innings pitched.
(Earned Runs × 9) ÷ Innings Pitched
Lower is better
A 2.50 ERA is excellent, 3.50 is good, 4.50 is average, and 5.50+ is poor.
The average number of walks and hits allowed by a pitcher per inning.
(Walks + Hits) ÷ Innings Pitched
Lower is better
A WHIP of 1.00 is elite, 1.30 is good, 1.50 is average, and 1.70+ is poor.
The average number of strikeouts a pitcher records per nine innings.
(Strikeouts × 9) ÷ Innings Pitched
Higher is better
10+ K/9 is elite, 8-9 is very good, 6-7 is average, below 5 is poor.
The average number of walks a pitcher allows per nine innings.
(Walks × 9) ÷ Innings Pitched
Lower is better
Under 2.0 BB/9 is excellent, 2.0-3.0 is good, 3.0-4.0 is average, 4.0+ is poor.
A metric that measures a pitcher's effectiveness at preventing home runs, walks, and hit by pitches, while causing strikeouts. Similar scale to ERA but removes defense from the equation.
FIP uses the same scale as ERA. A 3.00 FIP is excellent, 4.00 is average, 5.00+ is poor.
The total number of hits a pitcher has allowed to opposing batters.
Lower is better
Fewer hits allowed per inning pitched is better. Top pitchers allow less than 1 hit per inning.
The total number of batters a pitcher has struck out. A strikeout occurs when a batter receives three strikes.
Higher is better
200+ strikeouts in a season is excellent. Elite pitchers like Randy Johnson had 300+ in peak seasons.
The total number of batters a pitcher has walked (given a base on balls). A walk occurs when a pitcher throws four balls outside the strike zone.
Lower is better
Fewer walks shows better control. Elite pitchers average less than 2 walks per 9 innings.
The total number of innings a pitcher has pitched. Each out recorded counts as 1/3 of an inning.
200+ innings pitched in a season indicates durability. Ace starters typically pitch 180-220 innings.
A statistic credited to a relief pitcher who finishes a game for the winning team under certain conditions, preserving a narrow lead.
40+ saves in a season is excellent for a closer. The record is 62 saves by Francisco Rodriguez in 2008.