Since 1900, Larry Harlow has the highest ERA with 500+ plate appearances in a season, with an ERA of 67.50 in his rookie season in 1978.
| NAME | ERA | PA | SEASON | TM | G | W | L | W% | GS | SO | CG | SHO | SV | IP | H | ER | R | HR | BB | HBP | GF | IBB | TBF | WP | K/9 | BB/9 | K/BB | HR/9 | K% | BB% | WHIP | BABIP | RA | ERA- | FIP | FIP- | H/9 | PRAA | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 |  | L. Harlow | 67.50 | 521 | 1978 |  BAL | 1 | 0 | 0 | 0 | 1 | 0 | 0 | 0 | 0.2 | 2 | 5 | 5 | 1 | 4 | 0 | 0 | 0 | 8 | 1 | 13.50 | 54.00 | 0.25 | 13.50 | 12.5 | 50.0 | 9.00 | .500 | 67.50 | 1888 | 37.07 | 996 | 27.00 | -2.5 | |
| 2 | | L. Biittner | 40.50 | 532 | 1977 |  CHC | 1 | 0 | 0 | 0 | 3 | 0 | 0 | 0 | 1.1 | 5 | 6 | 6 | 3 | 1 | 0 | 1 | 0 | 10 | 0 | 20.25 | 6.75 | 3.00 | 20.25 | 30.0 | 10.0 | 4.50 | .667 | 40.50 | 942 | 29.73 | 711 | 33.75 | -3.5 | |
| 3 | | D. Bell | 36.00 | 622 | 2000 |  NYM | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1.0 | 3 | 4 | 5 | 0 | 3 | 0 | 1 | 0 | 10 | 0 | 0.00 | 27.00 | 0.00 | 0.00 | 0.0 | 30.0 | 6.00 | .429 | 45.00 | 810 | 12.13 | 266 | 27.00 | -0.9 | |
| 4 | | L. Thomas | 27.00 | 682 | 2023 |  WSH | 1 | 0 | 0 | 0 | 1 | 0 | 0 | 0 | 1.0 | 3 | 3 | 3 | 1 | 0 | 0 | 1 | 0 | 6 | 0 | 9.00 | 0.00 | 9.00 | 16.7 | 0.0 | 3.00 | .500 | 27.00 | 623 | 14.25 | 323 | 27.00 | -1.1 | ||
| 5 |  | D. Peralta | 27.00 | 538 | 2021 |  ARI | 1 | 0 | 0 | 0 | 1 | 0 | 0 | 0 | 1.0 | 4 | 3 | 3 | 1 | 0 | 1 | 1 | 0 | 9 | 0 | 9.00 | 0.00 | 9.00 | 11.1 | 0.0 | 4.00 | .500 | 27.00 | 644 | 17.16 | 417 | 36.00 | -1.5 | ||
| 6 | | D. Taitt | 27.00 | 537 | 1928 |  BSA | 1 | 0 | 0 | 0 | 1 | 0 | 0 | 0 | 1.0 | 2 | 3 | 3 | 0 | 2 | 0 | 1 | 7 | 0 | 9.00 | 18.00 | 0.50 | 0.00 | 14.3 | 28.6 | 4.00 | .500 | 27.00 | 675 | 6.91 | 178 | 18.00 | -0.3 | ||
| 7 | | A. Gordon | 19.29 | 633 | 2019 |  KCR | 2 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 2.1 | 8 | 5 | 5 | 1 | 2 | 0 | 1 | 0 | 17 | 0 | 0.00 | 7.71 | 0.00 | 3.86 | 0.0 | 11.8 | 4.29 | .500 | 19.29 | 411 | 11.35 | 254 | 30.86 | -1.8 | |
| 8 | | Z. McKinstry | 18.00 | 518 | 2023 |  DET | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1.0 | 3 | 2 | 2 | 1 | 0 | 0 | 1 | 0 | 6 | 0 | 0.00 | 0.00 | 9.00 | 0.0 | 0.0 | 3.00 | .400 | 18.00 | 425 | 16.25 | 383 | 27.00 | -1.3 | ||
| 9 | | H. Dozier | 18.00 | 500 | 2022 | KCR | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1.0 | 2 | 2 | 2 | 1 | 1 | 0 | 1 | 0 | 6 | 0 | 0.00 | 9.00 | 0.00 | 9.00 | 0.0 | 16.7 | 3.00 | .250 | 18.00 | 446 | 19.11 | 490 | 18.00 | -1.7 | |
| 10 | | W. Merrifield | 18.00 | 550 | 2022 | TOT | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1.0 | 2 | 2 | 2 | 1 | 0 | 1 | 1 | 0 | 6 | 0 | 0.00 | 0.00 | 9.00 | 0.0 | 0.0 | 2.00 | .250 | 18.00 | 469 | 19.11 | 476 | 18.00 | -1.6 | ||
| 11 | | H. Alberto | 18.00 | 550 | 2019 | BAL | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1.0 | 1 | 2 | 2 | 1 | 2 | 1 | 1 | 0 | 7 | 0 | 0.00 | 18.00 | 0.00 | 9.00 | 0.0 | 28.6 | 3.00 | .000 | 18.00 | 383 | 25.20 | 521 | 9.00 | -2.1 | |
| 12 | | A. Dark | 18.00 | 693 | 1953 |  NYG | 1 | 0 | 0 | 1 | 0 | 0 | 0 | 0 | 1.0 | 1 | 2 | 2 | 1 | 1 | 0 | 0 | 5 | 0 | 0.00 | 9.00 | 0.00 | 9.00 | 0.0 | 20.0 | 2.00 | .000 | 18.00 | 420 | 18.59 | 437 | 9.00 | -1.6 | ||
| 13 | | D. Lewis | 18.00 | 612 | 1913 | BSA | 1 | 0 | 0 | 0 | 1 | 0 | 0 | 0 | 1.0 | 3 | 2 | 2 | 0 | 0 | 0 | 1 | 6 | 0 | 9.00 | 0.00 | 0.00 | 16.7 | 0.0 | 3.00 | .600 | 18.00 | 627 | 0.56 | 19 | 27.00 | 0.3 | |||
| 14 | | G. Perring | 13.50 | 568 | 1914 |  KCP | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0.2 | 2 | 1 | 1 | 0 | 1 | 0 | 1 | 3 | 0 | 0.00 | 13.50 | 0.00 | 0.00 | 0.0 | 33.3 | 4.50 | 1.000 | 13.50 | 430 | 6.94 | 242 | 27.00 | -0.3 | ||
| 15 | | A. Dunn | 9.00 | 511 | 2014 | TOT | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1.0 | 2 | 1 | 1 | 0 | 1 | 0 | 1 | 0 | 6 | 0 | 0.00 | 9.00 | 0.00 | 0.00 | 0.0 | 16.7 | 3.00 | .400 | 9.00 | 234 | 6.13 | 157 | 18.00 | -0.2 | |
| 16 | | D. Gladden | 9.00 | 501 | 1989 |  MIN | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1.0 | 2 | 1 | 1 | 0 | 1 | 0 | 1 | 0 | 6 | 1 | 0.00 | 9.00 | 0.00 | 0.00 | 0.0 | 16.7 | 3.00 | .400 | 9.00 | 225 | 5.75 | 152 | 18.00 | -0.2 | |
| 17 | | T. Wallach | 9.00 | 639 | 1989 |  MON | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1.0 | 2 | 1 | 1 | 0 | 0 | 0 | 1 | 0 | 4 | 0 | 0.00 | 0.00 | 0.00 | 0.0 | 0.0 | 2.00 | .500 | 9.00 | 258 | 2.75 | 77 | 18.00 | 0.1 | ||
| 18 | | B. Campaneris | 9.00 | 634 | 1965 |  KCA | 1 | 0 | 0 | 0 | 1 | 0 | 0 | 0 | 1.0 | 1 | 1 | 1 | 0 | 2 | 0 | 0 | 0 | 5 | 0 | 9.00 | 18.00 | 0.50 | 0.00 | 20.0 | 40.0 | 3.00 | .500 | 9.00 | 255 | 6.52 | 179 | 9.00 | -0.3 | |
| 19 |  | B. Ruth | 9.00 | 693 | 1921 |  NYY | 2 | 2 | 0 | 1.000 | 1 | 2 | 0 | 0 | 0 | 9.0 | 14 | 9 | 10 | 1 | 9 | 0 | 1 | 49 | 0 | 2.00 | 9.00 | 0.22 | 1.00 | 4.1 | 18.4 | 2.56 | .351 | 10.00 | 210 | 7.10 | 170 | 14.00 | -2.9 | |
| 20 | | T. Speaker | 9.00 | 668 | 1914 | BSA | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1.0 | 2 | 1 | 1 | 0 | 0 | 0 | 1 | 4 | 0 | 0.00 | 0.00 | 0.00 | 0.0 | 0.0 | 2.00 | .500 | 9.00 | 336 | 2.44 | 88 | 18.00 | 0 | |||
| 21 | | C. Dolan | 9.00 | 559 | 1905 | TOT | 2 | 0 | 1 | .000 | 0 | 1 | 0 | 0 | 0 | 4.0 | 7 | 4 | 5 | 2 | 1 | 0 | 2 | 20 | 0 | 2.25 | 2.25 | 1.00 | 4.50 | 5.0 | 5.0 | 2.00 | .313 | 11.25 | 301 | 9.27 | 317 | 15.75 | -2.8 | |
| 22 | | J. Burkett | 9.00 | 636 | 1902 |  SLA | 1 | 0 | 1 | .000 | 0 | 2 | 0 | 0 | 0 | 1.0 | 4 | 1 | 4 | 0 | 1 | 0 | 0 | 8 | 0 | 18.00 | 9.00 | 2.00 | 0.00 | 25.0 | 12.5 | 5.00 | .800 | 36.00 | 263 | 1.67 | 51 | 36.00 | 0.2 | |
| 23 | | P. Carney | 9.00 | 580 | 1902 |  BSN | 2 | 0 | 1 | .000 | 1 | 3 | 0 | 0 | 0 | 5.0 | 6 | 5 | 5 | 1 | 3 | 1 | 1 | 24 | 0 | 5.40 | 5.40 | 1.00 | 1.80 | 12.5 | 12.5 | 1.80 | .313 | 9.00 | 311 | 6.47 | 213 | 10.80 | -1.8 | |
| 24 | | F. Isbell | 9.00 | 555 | 1902 |  CWS | 1 | 0 | 0 | 0 | 1 | 0 | 0 | 0 | 1.0 | 3 | 1 | 2 | 0 | 1 | 0 | 0 | 15 | 0 | 9.00 | 9.00 | 1.00 | 0.00 | 6.7 | 6.7 | 4.00 | .231 | 18.00 | 265 | 3.67 | 113 | 27.00 | -0.1 | ||
| 25 | | C. Seymour | 9.00 | 572 | 1902 | TOT | 1 | 0 | 0 | 0 | 2 | 0 | 0 | 0 | 3.0 | 4 | 3 | 3 | 0 | 3 | 0 | 0 | 16 | 1 | 6.00 | 9.00 | 0.67 | 0.00 | 12.5 | 18.8 | 2.33 | .364 | 9.00 | 297 | 4.33 | 136 | 12.00 | -0.3 | ||
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