| Career - Worst ERA | |||
| Rk | Player Name | Totals | |
| 1 | Brett Myers | 5.85 | |
| 2 | Randy Wolf | 5.57 | |
| 3 | Aaron Sele | 5.50 | |
| 4 | Kyle Lohse | 5.19 | |
| 5 | Carl Pavano | 5.18 | |
| 6 | Jason Marquis | 5.17 | |
| 7 | Edwin Jackson | 5.16 | |
| 8 | Mike Hampton | 5.12 | |
| 9 | Jon Garland | 5.12 | |
| 10 | Cal Eldred | 5.07 | |
| 11 | Aaron Cook | 5.06 | |
| 12 | Bronson Arroyo | 5.04 | |
| 13 | Jason Schmidt | 5.04 | |
| 14 | Scott Kazmir | 5.03 | |
| 15 | Chan Ho Park | 5.02 | |
| 16 | James Shields | 5.01 | |
| 17 | Jon Lieber | 4.99 | |
| 18 | C.C. Sabathia | 4.99 | |
| 19 | Jeremy Hellickson | 4.99 | |
| 20 | Brad Penny | 4.98 | |
| 21 | Jarrod Washburn | 4.97 | |
| 22 | Blake Snell | 4.97 | |
| 23 | Ramon Martinez | 4.96 | |
| 24 | Freddy Garcia | 4.96 | |
| 25 | Jason Hammel | 4.95 | |
| Single Season - Worst ERA | |||||
| Rk | Player Name | Totals | Year | ||
| 1 | Dave Stewart | 9.46 | 1994 | ||
| 2 | Donovan Osborne | 9.04 | 1994 | ||
| 3 | Frank Viola | 8.41 | 1994 | ||
| 4 | Jose Mesa | 8.30 | 1994 | ||
| 5 | Ben Rivera | 8.17 | 1994 | ||
| 6 | Trevor Wilson | 7.94 | 1994 | ||
| 7 | Victor Zambrano | 7.78 | 2004 | ||
| 8 | Ron Darling | 7.70 | 1994 | ||
| 9 | David Wells | 7.69 | 1994 | ||
| 10 | Cal Eldred | 7.54 | 1994 | ||
| 11 | Mike Morgan | 7.50 | 1994 | ||
| 12 | Randy Wolf | 7.49 | 2001 | ||
| 13 | Charlie Leibrandt | 7.48 | 1994 | ||
| 14 | Osvaldo Fernandez | 7.46 | 1997 | ||
| 15 | Chris Nabholz | 7.43 | 1994 | ||
| 16 | Roger Pavlik | 7.36 | 1994 | ||
| 17 | Aaron Civale | 7.35 | 2021 | ||
| 18 | Al Leiter | 7.26 | 2000 | ||
| 19 | Rick Sutcliffe | 7.21 | 1994 | ||
| 20 | Javier Vazquez | 7.20 | 2001 | ||
| 21 | Pat Hentgen | 7.17 | 1994 | ||
| 22 | Wilson Alvarez | 7.09 | 1994 | ||
| 23 | Jake Arrieta | 7.04 | 2018 | ||
| 24 | Grayson Rodriguez | 7.03 | 2024 | ||
| 25 | C.C. Sabathia | 7.02 | 2015 | ||