| ERA* Wins Losses Saves Games Games Started Complete Games Shutouts Innings Pitched Hits Allowed Homeruns Allowed Strikeouts Walks Allowed |
| Boston ERA* - Single Season Leaders |
| Rank | Player | Year | Value |
| 1 | Orval Overall | 2016 | 2.880 |
| 2 | Guy Hecker | 2016 | 3.010 |
| 3 | Jack Coombs | 2017 | 3.620 |
| 4 | Pud Galvin | 2017 | 3.820 |
| 5 | Guy Hecker | 2017 | 4.260 |
| 6 | Earl Moore | 2016 | 4.760 |
| 7 | Earl Moore | 2017 | 4.770 |
| 8 | Dolf Luque | 2016 | 5.850 |