| Player | Season | Losses |
|---|---|---|
| Mickey Welch (ELP) | 4 | 23 |
| Walter Johnson (STL) | 2 | 22 |
| Nolan Ryan (ELP) | 4 | 22 |
| Walter Johnson (VGA) | 1 | 19 |
| John Clarkson (NOH) | 1 | 18 |
| Carl Mays (SPB) | 4 | 18 |
| Steve Carlton (GRR) | 1 | 17 |
| Lefty Grove (PTL) | 3 | 17 |
| Bob Lemon (OTT) | 2 | 17 |
| Carl Mays (ELP) | 2 | 17 |
| Hoss Radbourn (SPB) | 1 | 17 |
| Johan Santana (OTT) | 3 | 17 |
| Pete Alexander (PTL) | 2 | 16 |
| Mordecai Brown (NOH) | 2 | 16 |
| Roger Clemens (PTL) | 1 | 16 |
| Catfish Hunter (NOH) | 1 | 16 |
| Joe McGinnity (ELP) | 2 | 16 |
| Mike Mussina (ELP) | 1 | 16 |
| Kid Nichols (ELP) | 1 | 16 |
| Cy Young (GRR) | 2 | 16 |
| Pete Alexander (SPB) | 4 | 15 |
| Chief Bender (PTL) | 4 | 15 |
| Mordecai Brown (NOH) | 3 | 15 |
| Jim Bunning (SPB) | 4 | 15 |
| Jack Chesbro (PTL) | 4 | 15 |
| Bob Feller (GRR) | 2 | 15 |
| Bob Gibson (PTL) | 2 | 15 |
| Bob Gibson (GRR) | 3 | 15 |
| Sandy Koufax (PTL) | 3 | 15 |
| Juan Marichal (VGA) | 2 | 15 |