Favorite Teams leagues are not included in Single-Season records. Records only remain for 10 seasons.
Single-Season Leaders (Losses)
Average
OBP
SLG
OPS
At Bats
Runs
Hits
Doubles
Triples
Homers
RBIs
Walks
Strikeouts
Stolen Bases
Caught Stealing
Sac Hits
Sac Fly
HBP
GIDP
D+/-
Wins
Losses
ERA
WHIP
Innings
Hits Allowed
HR Allowed
Walks (P)
Strikeouts (p)
Complete Games
Saves
Blown Saves
Shutouts
Quality Starts
Wild Pitches
Hit Batters
H/9
BB/9
SO/9
| 1. | Joss, Addie | (dunroche) | Detroit Tigers | 30 |
| 2. | McLain, Denny | (dunroche) | Chenango Wolves | 30 |
| 3. | Koufax, Sandy | (dunroche) | Chenango Wolves | 29 |
| 4. | McGinnity, Joe | (filler8) | Treasure Island ROBBERS | 29 |
| 5. | Sutton, Don | (dunroche) | South Dakota Dragons | 29 |
| 6. | Drysdale, Don | (filler8) | Algiers Point Poo Flingers | 29 |
| 7. | Sabathia, CC | (dynasty) | Florida Gators | 29 |
| 8. | Andujar, Joaquin | Albuquerque Mustangs | 29 | |
| 9. | Hershiser, Orel | (Poisonwildcat) | Shreveport Sharks | 29 |
| 10. | Hamels, Cole | (filler) | Springer Wolves | 29 |
| 11. | Plesac, Zach | (hanson) | Oconee Riverdawgs | 29 |
| 12. | Krukow, Mike | (govols1975) | Kenora Thistles | 28 |
| 13. | Swindell, Greg | (dynasty) | Denver Reds | 28 |
| 14. | White, Doc | (knottaverage) | Chicago Sippers | 28 |
| 15. | Cicotte, Eddie | (filler) | Nakatomi Die Hards | 28 |
| 16. | Halladay, Roy | (rreebe916) | South Dakota Suns | 28 |
| 17. | Wood, Joe | (whtsittou83) | Gwangju Craxy | 28 |
| 18. | Vander Meer, Johnny | (filler) | Riverdale Rams | 28 |
| 19. | Sutton, Don | (dynasty) | LITTLE ROCK RAZORBACKS | 28 |
| 20. | Bender, Chief | (filler8) | DELTA THUMPERS | 28 |
| 21. | Chance, Dean | (dynasty) | JACKSONVILLE JACKS | 28 |
| 22. | Cicotte, Eddie | (dynasty) | Toronto Devils | 28 |
| 23. | Sweeney, Charlie | (mdsyverson) | Saskatchewan Saskatoons | 28 |
| 24. | McLain, Denny | (dunroche) | Tuvalu Copras | 28 |
| 25. | Blyleven, Bert | (filler) | Houston Wolves | 28 |
| 26. | White, Doc | (filler) | Harrisburg Cougars | 28 |
| 27. | McGinnity, Joe | (filler8) | Halifax Hackers | 28 |
| 28. | Saberhagen, Bret | (dynasty) | Chenango Wolves | 28 |
| 29. | Shields, James | (jimgriddy) | Ellenton Traitors | 28 |
| 30. | Ford, Whitey | (ExposMe) | Huron Herons | 28 |
| 31. | Hendrix, Claude | (filler) | Seattle Pilots | 28 |
| 32. | Pfiester, Jack | (filler) | Seattle Pilots | 28 |
| 33. | Chesbro, Jack | (dynasty) | new jersey bandits | 28 |
| 34. | Taylor, Jack | (WorcWarr) | Worcester Warriors | 28 |
| 35. | Joss, Addie | (JohnHeidy) | Highland Hi-Ballers | 28 |
| 36. | Reulbach, Ed | (dynasty) | Escanaba Hilltoppers | 28 |
| 37. | Tanana, Frank | (filler8) | Orlando VA | 28 |
| 38. | Newcombe, Don | (filler8) | Chicago Cougars | 28 |
| 39. | Lyons, Ted | (OakTownAs66) | Butte Pirates | 28 |
| 40. | Drysdale, Don | (LDJS1947) | MISSOURI TIGERS | 28 |
| 41. | Iwakuma, Hisashi | (filler8) | Iowa Rhinos | 27 |
| 42. | Chesbro, Jack | (filler) | East County Crushers | 27 |
| 43. | Drabek, Doug | (dynasty) | Fillmore Warriors | 27 |
| 44. | Palmer, Jim | (dynasty) | Chicago Jets | 27 |
| 45. | Scott, Mike | (filler8) | Baltimore Burners | 27 |
| 46. | Millwood, Kevin | (filler) | Big Bad Blue Birds | 27 |
| 47. | King, Silver | (filler) | Watab River Wolves | 27 |
| 48. | Caldwell, Ray | (richgibson) | Pain Killers | 27 |
| 49. | Kaat, Jim | (Cubanlou) | Manhattan Americans | 27 |
| 50. | Norris, Mike | Lake Havasu Rain-2 | 27 |
