Single-Season Leaders for Win-Loss Pct
Minimum of 3.1 PA/G, 1.0 IP/G, and 0.1 decision/G for single-season leaderboards for rate statistics.
| Rank | Player | Win-Loss Pct | Year |
| 1. | Felix Hernandez | .938 | 2011 |
| 2. | Mike Pelfrey | .917 | 2011 |
| 3. | Wade Miller | .909 | 2004 |
| 4. | Cory Lidle | .889 | 2002 |
| 4. | AJ Burnett | .889 | 2003 |
| 4. | Jason Bergmann | .889 | 2008 |
