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| Single-Season ERA Leaderboard | |
| * - Indicates Hall of Fame |
| Rank | Player | ERA | IP | Year | Career Leaderboard |
| 1. | Stan Lugo | 1.215 | 274.0 | 1948 | |
| 2. | Stan Lugo | 1.751 | 257.0 | 1947 | |
| 3. | James Nickerson | 2.141 | 206.0 | 1948 | |
| 4. | Stan Lugo | 2.394 | 244.3 | 1949 | |
| 5. | Roger Kirwan | 2.488 | 173.7 | 1948 | |
| 6. | Robert Lerman | 2.489 | 264.0 | 1950 | |
| 7. | Domingo Contreras | 2.594 | 281.0 | 1949 | |
| 8. | Stephen McMaster | 2.652 | 281.7 | 1948 | |
| 9. | Paul Bravo | 2.871 | 200.7 | 1948 | |
| 10. | Jose Rao | 2.943 | 192.7 | 1950 | |
| 11. | Earle Olivier | 3.012 | 248.0 | 1947 | |
| 12. | Joseph Hale | 3.019 | 265.3 | 1949 | |
| 13. | Craig Riemer | 3.051 | 277.3 | 1947 | |
| 14. | Lucien Pillar | 3.084 | 286.0 | 1950 | |
| 15. | Robert Lerman | 3.154 | 279.7 | 1949 | |
| 16. | Dwight Roesch | 3.179 | 257.7 | 1949 | |
| 17. | Donald Walker | 3.196 | 245.0 | 1948 | |
| 18. | Bud Bartley | 3.212 | 193.3 | 1947 | |
| 19. | Domingo Contreras | 3.215 | 288.3 | 1947 | |
| 20. | Pelayo Torres | 3.242 | 194.3 | 1950 | |
| 21. | Corey Hill | 3.243 | 272.0 | 1950 | |
| 22. | Robert Lerman | 3.249 | 268.7 | 1948 | |
| 23. | Michael Edwards | 3.267 | 187.3 | 1950 | |
| 24. | James Hanselman | 3.283 | 268.7 | 1950 | |
| 25. | Domingo Contreras | 3.298 | 278.3 | 1948 | |
| 26. | Robert Carreiro | 3.318 | 179.0 | 1950 | |
| 27. | Joseph Hale | 3.337 | 267.0 | 1948 | |
| 28. | Joshua Cook | 3.350 | 271.3 | 1950 | |
| 29. | Kendry Lizarraga | 3.357 | 254.7 | 1947 | |
| 30. | Corey Hill | 3.361 | 243.7 | 1948 | |
| 31. | Kendry Lizarraga | 3.362 | 254.3 | 1948 | |
| 32. | Joshua Cook | 3.384 | 258.0 | 1948 | |
| 33. | Terry Lobdell | 3.385 | 220.7 | 1950 | |
| 34. | Jesse Nelson | 3.391 | 217.7 | 1948 | |
| 35. | Lucien Pillar | 3.392 | 268.0 | 1948 | |
| 36. | Daniel Adams | 3.392 | 262.7 | 1948 | |
| 37. | Joseph Eley | 3.397 | 206.7 | 1949 | |
| 38. | Dwight Roesch | 3.434 | 267.3 | 1948 | |
| 39. | Lucien Pillar | 3.465 | 262.3 | 1949 | |
| 40. | Roger Kirwan | 3.470 | 259.3 | 1947 | |
| 41. | James Ingles | 3.477 | 176.0 | 1950 | |
| 42. | Ryan Canizales | 3.497 | 321.7 | 1950 | |
| 43. | James Hanselman | 3.514 | 243.3 | 1947 | |
| 44. | Lucien Pillar | 3.523 | 265.7 | 1947 | |
| 45. | Eric Brown | 3.525 | 247.7 | 1948 | |
| 46. | Roger Kirwan | 3.563 | 257.7 | 1949 | |
| 47. | William Noriega | 3.568 | 239.7 | 1950 | |
| 48. | Miichirou Kotaro | 3.569 | 249.7 | 1950 | |
| 49. | Mark Carrasquillo | 3.569 | 232.0 | 1948 | |
| 50. | James Riordan | 3.582 | 228.7 | 1949 | |
| 51. | Earle Olivier | 3.590 | 235.7 | 1949 | |
| 52. | Albert Vogel | 3.602 | 252.3 | 1947 | |
| 53. | Richard Cunningham | 3.605 | 229.7 | 1948 | |
| 54. | Stephen McMaster | 3.620 | 271.0 | 1949 | |
| 55. | Robert Lerman | 3.630 | 282.7 | 1947 | |
| 56. | Jon Eaton | 3.631 | 215.7 | 1947 | |
| 57. | Abel Ceja | 3.635 | 255.0 | 1947 | |
| 58. | Jarvis Inabinet | 3.664 | 253.0 | 1950 | |
| 59. | James Hanselman | 3.666 | 262.7 | 1948 | |
| 60. | Virgil Rice | 3.672 | 250.0 | 1948 | |
| 61. | Lavern Bessler | 3.672 | 208.3 | 1948 | |
| 62. | Gerald Sarno | 3.677 | 264.3 | 1948 | |
| 63. | James Riordan | 3.680 | 239.7 | 1948 | |
| 64. | Tommie Guernsey | 3.680 | 276.3 | 1948 | |
| 65. | Marvin Shope | 3.685 | 254.0 | 1950 | |
| 66. | Daniel Elliott | 3.690 | 261.0 | 1948 | |
| 67. | Kendry Lizarraga | 3.694 | 243.7 | 1950 | |
| 68. | Roderick Horner | 3.711 | 184.3 | 1948 | |
| 69. | Roderick Mooney | 3.715 | 198.7 | 1947 | |
| 70. | Corey Hill | 3.732 | 246.0 | 1949 | |
| 71. | Robert Carreiro | 3.736 | 212.0 | 1949 | |
| 72. | Donald Walker | 3.738 | 248.0 | 1950 | |
| 73. | Carlos Pacheco | 3.739 | 272.0 | 1950 | |
| 74. | Gerald Sarno | 3.755 | 275.7 | 1950 | |
| 75. | James Hanselman | 3.760 | 263.3 | 1949 | |
| 76. | Kendry Lizarraga | 3.762 | 244.0 | 1949 | |
| 77. | Joseph Dierks | 3.783 | 226.0 | 1948 | |
| 78. | Ian Corpus | 3.786 | 180.7 | 1947 | |
| 79. | Joel Lopez | 3.787 | 164.0 | 1949 | |
| 80. | Gerald Sarno | 3.795 | 246.7 | 1949 | |
| Marvin Shope | 3.795 | 246.7 | 1948 | ||
| 82. | Marvin Shope | 3.795 | 249.0 | 1949 | |
| 83. | Joseph Hale | 3.815 | 276.0 | 1947 | |
| 84. | Dwight Roesch | 3.852 | 247.7 | 1947 | |
| 85. | Lavern Bessler | 3.857 | 252.0 | 1947 | |
| 86. | Robert Carreiro | 3.869 | 214.0 | 1948 | |
| 87. | Casey Stutzman | 3.871 | 190.7 | 1947 | |
| 88. | Joshua Cook | 3.877 | 255.3 | 1947 | |
| 89. | Earle Olivier | 3.879 | 236.7 | 1950 | |
| 90. | Andrew Tarpley | 3.897 | 196.3 | 1950 | |
| 91. | William Noriega | 3.933 | 203.7 | 1947 | |
| 92. | Gary Smith | 3.937 | 258.3 | 1947 | |
| 93. | Paul Bravo | 3.940 | 249.0 | 1947 | |
| 94. | Carlos Pacheco | 3.947 | 273.7 | 1947 | |
| 95. | Joseph Dierks | 3.970 | 251.7 | 1950 | |
| 96. | Joseph Eley | 3.976 | 237.7 | 1950 | |
| 97. | Domingo Contreras | 3.985 | 221.3 | 1950 | |
| 98. | Mark Carrasquillo | 3.998 | 182.3 | 1947 | |
| 99. | Joseph Hale | 4.001 | 294.7 | 1950 | |
| 100. | Edward Plaisance | 4.002 | 186.7 | 1950 |
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