| Career - Worst ERA | |||
| Rk | Player Name | Totals | |
| 1 | Adam Eaton | 5.62 | |
| 2 | Matt Garza | 4.99 | |
| 3 | David Cone | 4.85 | |
| 4 | Framber Valdez | 4.74 | |
| 5 | Mark Mulder | 4.63 | |
| 6 | Gio Gonzalez | 4.48 | |
| 7 | Sandy Alcantara | 4.45 | |
| 8 | Noah Lowry | 4.43 | |
| 9 | Yovani Gallardo | 4.36 | |
| 10 | Zach Davies | 4.19 | |
| 11 | Alex Fernandez | 4.14 | |
| 12 | Woody Williams | 4.09 | |
| 13 | Hiroki Kuroda | 3.96 | |
| 14 | Tyson Ross | 3.78 | |
| 15 | Danny Duffy | 3.74 | |
| 16 | Jered Weaver | 3.72 | |
| 17 | Walker Buehler | 3.72 | |
| 18 | Ben McDonald | 3.71 | |
| 19 | Roger Clemens | 3.49 | |
| 20 | Jason Frasor | 3.47 | |
| 21 | Melido Perez | 3.44 | |
| 22 | Alex Colome | 3.20 | |
| 23 | Greg Maddux | 3.06 | |
| 24 | Juan Guzman | 2.91 | |
| 25 | Jesse Crain | 2.68 | |
| Single Season - Worst ERA | |||||
| Rk | Player Name | Totals | Year | ||
| 1 | Brian Lawrence | 6.67 | 2004 | ||
| 2 | Fernando Valenzuela | 5.82 | 1994 | ||
| 3 | Doug Davis | 5.62 | 2006 | ||
| 4 | Adam Eaton | 5.45 | 2006 | ||
| 5 | Framber Valdez | 5.32 | 2024 | ||
| 6 | Gio Gonzalez | 5.23 | 2016 | ||
| 7 | Willie Banks | 5.15 | 1994 | ||
| 8 | Mark Mulder | 5.07 | 2004 | ||
| 9 | Greg Maddux | 5.05 | 2000 | ||
| 10 | Eddie Butler | 5.02 | 2018 | ||
| 11 | Bruce Chen | 4.99 | 2001 | ||
| 12 | Matt Garza | 4.99 | 2010 | ||
| 13 | Adam Eaton | 4.98 | 2005 | ||
| 14 | Greg Maddux | 4.96 | 1991 | ||
| 15 | Miles Mikolas | 4.94 | 2023 | ||
| 16 | David Cone | 4.90 | 1991 | ||
| 17 | Matt Garza | 4.88 | 2009 | ||
| 18 | Aaron Laffey | 4.83 | 2009 | ||
| 19 | Zack Littell | 4.82 | 2024 | ||
| 20 | Framber Valdez | 4.80 | 2022 | ||
| 21 | David Cone | 4.79 | 1990 | ||
| 22 | Carl Pavano | 4.79 | 2001 | ||
| 23 | Hiroki Kuroda | 4.73 | 2010 | ||
| 24 | Sandy Alcantara | 4.69 | 2024 | ||
| 25 | Dave Bush | 4.68 | 2007 | ||