| Rank | Team | Earned Run Average | Record |
| 1. | Texas Rangers, 2003 | 6.5397 | 57-105 |
| 2. | Seattle Mariners, 1977 | 6.2795 | 52-110 |
| 3. | Texas Rangers, 2000 | 6.1711 | 61-101 |
| 4. | Colorado Rockies, 1999 | 6.1596 | 58-104 |
| 5. | Texas Rangers, 2008 | 6.1246 | 55-107 |
| 6. | Colorado Rockies, 1994 | 6.1076 | 60-102 |
| 7. | Colorado Rockies, 2004 | 6.0933 | 63-99 |
| 8. | Milwaukee Brewers, 1995 | 6.0477 | 64-98 |
| 9. | Oakland A's, 1977 | 6.0339 | 47-115 |
| 10. | Seattle Mariners, 2011 | 6.0224 | 42-120 |
| 11. | Texas Rangers, 2002 | 6.0166 | 66-96 |
| 12. | Toronto Blue Jays, 2009 | 5.9782 | 48-114 |
| 13. | Colorado Rockies, 1996 | 5.9428 | 75-87 |
| 14. | Minnesota Twins, 1996 | 5.9195 | 76-86 |
| 15. | Texas Rangers, 2001 | 5.8950 | 64-98 |
| 16. | Colorado Rockies, 1998 | 5.8607 | 60-102 |
| 17. | Milwaukee Brewers, 1999 | 5.7718 | 65-97 |
| 18. | Detroit Tigers, 1994 | 5.7617 | 73-89 |
| 19. | Kansas City Royals, 2000 | 5.7524 | 56-106 |
| 20. | Minnesota Twins, 1994 | 5.7242 | 73-89 |
| 21. | Baltimore Orioles, 2000 | 5.7125 | 66-96 |
| 22. | St. Louis Cardinals, 2000 | 5.7057 | 61-101 |
| 23. | Texas Rangers, 2006 | 5.6978 | 70-92 |
| 24. | Milwaukee Brewers, 2009 | 5.6762 | 47-115 |
| 25. | Toronto Blue Jays, 2012 | 5.6487 | 52-110 |
| 26. | Chicago White Sox, 1985 | 5.6354 | 53-109 |
| 27. | Colorado Rockies, 2002 | 5.6294 | 54-108 |
| 28. | Toronto Blue Jays, 2001 | 5.6219 | 54-108 |
| 29. | Oakland A's, 1997 | 5.6151 | 62-100 |
| 30. | Baltimore Orioles, 1987 | 5.6012 | 59-103 |
| 31. | Minnesota Twins, 1975 | 5.5824 | 63-99 |
| 32. | Colorado Rockies, 2001 | 5.5805 | 73-89 |
| 33. | Seattle Mariners, 1979 | 5.5800 | 68-94 |
| 34. | St. Louis Cardinals, 1994 | 5.5642 | 67-95 |
| 35. | St. Louis Browns, 1936 | 5.5557 | 73-81 |
| 36. | Colorado Rockies, 2000 | 5.5473 | 85-77 |
| 37. | Chicago White Sox, 1998 | 5.5369 | 69-93 |
| 38. | Seattle Mariners, 2007 | 5.5364 | 59-103 |
| 39. | Milwaukee Brewers, 1994 | 5.5353 | 60-102 |
| 40. | Toronto Blue Jays, 2004 | 5.5283 | 60-102 |
| 41. | Baltimore Orioles, 2002 | 5.5202 | 57-105 |
| 42. | Texas Rangers, 2004 | 5.5192 | 74-88 |
| 43. | Milwaukee Brewers, 2001 | 5.4926 | 79-83 |
| 44. | Florida Marlins, 1994 | 5.4889 | 65-97 |
| 45. | Detroit Tigers, 1995 | 5.4854 | 66-96 |
| 46. | Texas Rangers, 1997 | 5.4760 | 80-82 |
| 47. | Boston Red Sox, 2001 | 5.4713 | 60-102 |
| 48. | St. Louis Cardinals, 1956 | 5.4527 | 48-106 |
| 49. | Washington Nationals, 2006 | 5.4466 | 57-105 |
| 50. | Seattle Mariners, 2010 | 5.4414 | 40-122 |