20 pitchers are tied for the best ERA with a win percentage below .400 in a season, with an ERA of 0.00. The first three are Thyago Vieira in 2023 and Oliver Perez and Angel Zerpa in 2021.
| NAME | ERA | W% | SEASON | TM | W | L | G | 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 |  | T. Vieira | 0.00 | .000 | 2023 |  MIL | 0 | 1 | 2 | 0 | 2 | 0 | 0 | 0 | 3.0 | 0 | 0 | 1 | 0 | 1 | 0 | 2 | 0 | 10 | 0 | 6.00 | 3.00 | 2.00 | 0.00 | 20.0 | 10.0 | 0.33 | .000 | 3.00 | 0 | 2.92 | 66 | 0.00 | 0.5 |
| 2 | | O. Perez | 0.00 | .000 | 2021 |  CLE | 0 | 1 | 5 | 0 | 4 | 0 | 0 | 0 | 3.2 | 5 | 0 | 1 | 0 | 1 | 0 | 3 | 1 | 18 | 0 | 9.82 | 2.45 | 4.00 | 0.00 | 22.2 | 5.6 | 1.64 | .385 | 2.45 | 0 | 1.80 | 43 | 12.27 | 1 |
| 3 | | A. Zerpa | 0.00 | .000 | 2021 |  KCR | 0 | 1 | 1 | 1 | 4 | 0 | 0 | 0 | 5.0 | 3 | 0 | 2 | 0 | 1 | 0 | 0 | 0 | 20 | 0 | 7.20 | 1.80 | 4.00 | 0.00 | 20.0 | 5.0 | 0.80 | .200 | 3.60 | 0 | 2.16 | 51 | 5.40 | 1.2 |
| 4 | | N. Karns | 0.00 | .000 | 2019 |  BAL | 0 | 1 | 4 | 2 | 5 | 0 | 0 | 0 | 5.1 | 7 | 0 | 1 | 0 | 3 | 1 | 1 | 0 | 25 | 1 | 8.44 | 5.06 | 1.67 | 0.00 | 20.0 | 12.0 | 1.88 | .438 | 1.69 | 0 | 3.58 | 74 | 11.81 | 0.7 |
| 5 | | J. Minshall | 0.00 | .000 | 1974 |  PIT | 0 | 1 | 5 | 0 | 3 | 0 | 0 | 0 | 4.1 | 1 | 0 | 1 | 0 | 2 | 0 | 1 | 1 | 15 | 0 | 6.23 | 4.15 | 1.50 | 0.00 | 20.0 | 13.3 | 0.69 | .100 | 2.08 | 0 | 2.57 | 71 | 2.08 | 0.5 |
| 6 | | A. Santorini | 0.00 | .000 | 1968 |  ATL | 0 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 3.0 | 4 | 0 | 4 | 1 | 0 | 0 | 0 | 0 | 14 | 1 | 0.00 | 0.00 | 3.00 | 0.0 | 0.0 | 1.33 | .231 | 12.00 | 0 | 6.72 | 235 | 12.00 | -1.3 | |
| 7 | | A. Brice | 0.00 | .000 | 1961 |  CWS | 0 | 1 | 3 | 0 | 3 | 0 | 0 | 0 | 3.1 | 4 | 0 | 2 | 0 | 3 | 0 | 0 | 0 | 16 | 0 | 8.10 | 8.10 | 1.00 | 0.00 | 18.8 | 18.8 | 2.10 | .400 | 5.40 | 0 | 3.47 | 87 | 10.80 | 0.2 |
| 8 | | W. Miller | 0.00 | .000 | 1944 |  NYG | 0 | 1 | 4 | 0 | 2 | 0 | 0 | 0 | 5.0 | 1 | 0 | 2 | 0 | 4 | 0 | 3 | 21 | 0 | 3.60 | 7.20 | 0.50 | 0.00 | 9.5 | 19.0 | 1.00 | .067 | 3.60 | 0 | 4.14 | 112 | 1.80 | -0.2 | |
| 9 | | D. Mails | 0.00 | .000 | 1926 |  SLN | 0 | 1 | 1 | 0 | 1 | 0 | 0 | 0 | 1.0 | 2 | 0 | 1 | 0 | 1 | 0 | 0 | 8 | 0 | 9.00 | 9.00 | 1.00 | 0.00 | 12.5 | 12.5 | 3.00 | .333 | 9.00 | 0 | 3.91 | 100 | 18.00 | 0 | |
| 10 | | C. Roe | 0.00 | .000 | 1923 |  WSH | 0 | 1 | 1 | 1 | 2 | 0 | 0 | 0 | 1.2 | 0 | 0 | 4 | 0 | 6 | 0 | 0 | 12 | 3 | 10.80 | 32.40 | 0.33 | 0.00 | 16.7 | 50.0 | 3.60 | .000 | 21.60 | 0 | 11.33 | 297 | 0.00 | -1.5 | |
| 11 | | E. Erickson | 0.00 | .000 | 1914 | NYG | 0 | 1 | 1 | 1 | 3 | 0 | 0 | 0 | 5.0 | 8 | 0 | 7 | 0 | 3 | 0 | 0 | 27 | 0 | 5.40 | 5.40 | 1.00 | 0.00 | 11.1 | 11.1 | 2.20 | .381 | 12.60 | 0 | 3.04 | 106 | 14.40 | -0.1 | |
| 12 | | D. Sherman | 0.00 | .000 | 1914 |  CHF | 0 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 0.1 | 0 | 0 | 2 | 0 | 2 | 0 | 0 | 3 | 0 | 0.00 | 54.00 | 0.00 | 0.00 | 0.0 | 66.7 | 6.00 | .000 | 54.00 | 0 | 20.44 | 742 | 0.00 | -0.7 | |
| 13 | | L. Williams | 0.00 | .000 | 1914 |  DET | 0 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 1.0 | 3 | 0 | 5 | 0 | 2 | 0 | 0 | 9 | 0 | 0.00 | 18.00 | 0.00 | 0.00 | 0.0 | 22.2 | 5.00 | .429 | 45.00 | 0 | 8.44 | 292 | 27.00 | -0.6 | |
| 14 | | R. Aitchison | 0.00 | .000 | 1911 |  BKN | 0 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 1.1 | 1 | 0 | 2 | 0 | 1 | 0 | 0 | 6 | 0 | 0.00 | 6.75 | 0.00 | 0.00 | 0.0 | 16.7 | 1.50 | .200 | 13.50 | 0 | 5.02 | 146 | 6.75 | -0.2 | |
| 15 | | H. Armstrong | 0.00 | .000 | 1911 |  PHA | 0 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 3.0 | 3 | 0 | 2 | 0 | 1 | 0 | 1 | 12 | 0 | 0.00 | 3.00 | 0.00 | 0.00 | 0.0 | 8.3 | 1.33 | .273 | 6.00 | 0 | 3.77 | 122 | 9.00 | -0.2 | |
| 16 | | J. Keenan | 0.00 | .000 | 1891 | CNA | 0 | 1 | 1 | 1 | 5 | 1 | 0 | 0 | 8.0 | 6 | 0 | 9 | 0 | 4 | 1 | 0 | 35 | 0 | 5.63 | 4.50 | 1.25 | 0.00 | 14.3 | 11.4 | 1.25 | .240 | 10.13 | 0 | 3.16 | 84 | 6.75 | 0.6 | |
| 17 | | J. Fogarty | 0.00 | .000 | 1886 |  PHN | 0 | 1 | 1 | 0 | 4 | 0 | 0 | 0 | 6.0 | 7 | 0 | 6 | 0 | 0 | 1 | 28 | 1 | 6.00 | 0.00 | 0.00 | 14.3 | 0.0 | 1.17 | 9.00 | 0 | 1.77 | 55 | 10.50 | 1 | ||||
| 18 | | F. Kreeger | 0.00 | .000 | 1884 | KCC | 0 | 1 | 1 | 1 | 3 | 0 | 0 | 0 | 7.0 | 9 | 0 | 8 | 0 | 5 | 0 | 36 | 0 | 3.86 | 6.43 | 0.60 | 0.00 | 8.3 | 13.9 | 2.00 | 10.29 | 0 | 4.56 | 183 | 11.57 | -1.8 | |||
| 19 | | C. Comiskey | 0.00 | .000 | 1882 | STL | 0 | 1 | 2 | 1 | 2 | 1 | 0 | 0 | 8.0 | 12 | 0 | 8 | 0 | 3 | 0 | 40 | 1 | 2.25 | 3.38 | 0.67 | 0.00 | 5.0 | 7.5 | 1.88 | 9.00 | 0 | 3.39 | 118 | 13.50 | -0.4 | |||
| 20 | | F. Lafferty | 0.00 | .000 | 1876 |  PHI | 0 | 1 | 1 | 1 | 0 | 1 | 0 | 0 | 9.0 | 5 | 0 | 3 | 0 | 0 | 0 | 33 | 0 | 0.00 | 0.00 | 0.00 | 0.0 | 0.0 | 0.56 | 3.00 | 0 | 2.23 | 91 | 5.00 | 0.4 | ||||
| 21 | | R. Bare | 0.54 | .000 | 1972 | STL | 0 | 1 | 14 | 0 | 5 | 0 | 0 | 1 | 16.2 | 18 | 1 | 2 | 0 | 6 | 0 | 5 | 2 | 71 | 0 | 2.70 | 3.24 | 0.83 | 0.00 | 7.0 | 8.5 | 1.44 | .300 | 1.08 | 15 | 2.87 | 86 | 9.72 | 0.9 |
| 22 | | J. Miljus | 0.60 | .000 | 1917 | BKN | 0 | 1 | 4 | 1 | 9 | 1 | 0 | 0 | 15.0 | 14 | 1 | 3 | 0 | 8 | 3 | 3 | 70 | 1 | 5.40 | 4.80 | 1.13 | 0.00 | 12.9 | 11.4 | 1.47 | .280 | 1.80 | 22 | 3.26 | 126 | 8.40 | -1.1 | |
| 23 | | C. Sadler | 0.67 | .000 | 2021 |  SEA | 0 | 1 | 42 | 0 | 37 | 0 | 0 | 0 | 40.1 | 19 | 3 | 4 | 1 | 10 | 1 | 2 | 0 | 145 | 2 | 8.26 | 2.23 | 3.70 | 0.22 | 25.5 | 6.9 | 0.72 | .188 | 0.89 | 16 | 2.47 | 59 | 4.24 | 7.7 |
| 24 | | H. Aguirre | 0.69 | .333 | 1968 |  LAD | 1 | 2 | 25 | 0 | 25 | 0 | 0 | 3 | 39.0 | 32 | 3 | 8 | 0 | 13 | 3 | 16 | 3 | 167 | 4 | 5.77 | 3.00 | 1.92 | 0.00 | 15.0 | 7.8 | 1.15 | .254 | 1.85 | 25 | 2.33 | 90 | 7.38 | 1.1 |
| 25 | | R. Hernandez | 0.73 | .000 | 1971 | PIT | 0 | 1 | 10 | 0 | 7 | 0 | 0 | 4 | 12.1 | 5 | 1 | 1 | 0 | 2 | 0 | 7 | 1 | 44 | 0 | 5.11 | 1.46 | 3.50 | 0.00 | 15.9 | 4.5 | 0.57 | .143 | 0.73 | 22 | 1.80 | 55 | 3.65 | 2.1 |
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