Justin Masterson career ERA
4.31Career Regular Season
Justin Masterson has a career ERA of 4.31 over 8 regular seasons.
- Best season on file: 3.16 in 2008.
- Most recent: 5.61 in 2015.
Average of 8 regular seasons, 2008 through 2015. Figures come from ESPN's box scores and were last read on September 23, 2026.
| GP: Games the player appeared in, however briefly. | W: Games in which this pitcher was credited with the win. | L: Games in which this pitcher was charged with the loss. | ERA: Earned runs allowed per nine innings pitched — lower is better. Under 3.00 is excellent. | IP: Innings pitched. The decimal counts outs, so 6.2 is six innings and two more outs. | K: Batters this pitcher struck out. | BB: Times the batter reached first base on four balls. | WHIP: Walks and hits allowed per inning pitched — lower is better. Around 1.00 is elite. | SV: Games finished by protecting a narrow lead to the last out. | ||
|---|---|---|---|---|---|---|---|---|---|---|
| 2008 |  BOS | 36 | 6 | 5 | 3.16 | 88.1 | 68 | 40 | 1.22 | 0 |
| 2009 |  BOS/CLE | 42 | 4 | 10 | 4.52 | 129.1 | 119 | 60 | 1.45 | 0 |
| 2010 | CLE | 34 | 6 | 13 | 4.70 | 180.0 | 140 | 73 | 1.50 | 0 |
| 2011 | CLE | 34 | 12 | 10 | 3.21 | 216.0 | 158 | 65 | 1.28 | 0 |
| 2012 | CLE | 34 | 11 | 15 | 4.93 | 206.1 | 159 | 88 | 1.45 | 0 |
| 2013 | CLE | 32 | 14 | 10 | 3.45 | 193.0 | 195 | 76 | 1.20 | 0 |
| 2014 |  CLE/STL | 28 | 7 | 9 | 5.88 | 128.2 | 116 | 69 | 1.63 | 0 |
| 2015 | BOS | 18 | 4 | 2 | 5.61 | 59.1 | 49 | 27 | 1.60 | 0 |
What the columns mean: W · L · ERA · IP · K · BB · WHIP · SV