I don't have anything for this season, but Aroldis Chapman had the highest K/9 by a left-handed relief pitcher with 25.0+ innings pitched in 2024, with 14.30 per nine innings.
Interpreted as:
left handed relief pitchers with most strikeouts per 9 innings 2023 while pitching at least 25 innings this regular season| NAME | K/9 | IP | SEASON | TM | G | W | L | W% | GS | ERA | SO | CG | SHO | SV | H | ER | R | HR | BB | HBP | GF | IBB | TBF | WP | BB/9 | K/BB | HR/9 | K% | BB% | WHIP | BABIP | RA | H/9 | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 |  | A. Chapman | 14.30 | 61.2 | 2024 |  PIT | 68 | 5 | 5 | .500 | 0 | 3.79 | 98 | 0 | 0 | 14 | 44 | 26 | 31 | 5 | 39 | 2 | 18 | 0 | 265 | 4 | 5.69 | 2.51 | 0.73 | 37.0 | 14.7 | 1.35 | .322 | 4.52 | 6.42 |
| 2 |  | J. Hader | 13.31 | 71.0 | 2024 |  HOU | 71 | 8 | 8 | .500 | 0 | 3.80 | 105 | 0 | 0 | 34 | 43 | 30 | 33 | 12 | 25 | 1 | 62 | 0 | 278 | 4 | 3.17 | 4.20 | 1.52 | 37.8 | 9.0 | 0.96 | .230 | 4.18 | 5.45 |
| 3 |  | A. Nardi | 12.68 | 49.2 | 2024 |  MIA | 59 | 3 | 2 | .600 | 0 | 5.07 | 70 | 0 | 0 | 0 | 44 | 28 | 29 | 7 | 18 | 1 | 4 | 1 | 210 | 1 | 3.26 | 3.89 | 1.27 | 33.3 | 8.6 | 1.25 | .325 | 5.26 | 7.97 |
| 4 |  | E. Miller | 12.07 | 56.2 | 2024 |  SFG | 63 | 4 | 5 | .444 | 0 | 4.45 | 76 | 0 | 0 | 0 | 43 | 28 | 31 | 6 | 32 | 1 | 11 | 0 | 243 | 1 | 5.08 | 2.38 | 0.95 | 31.3 | 13.2 | 1.32 | .289 | 4.92 | 6.83 |
| 5 |  | A.J. Puk | 11.86 | 57.2 | 2024 | TOT | 58 | 4 | 5 | .444 | 0 | 1.72 | 76 | 0 | 0 | 3 | 32 | 11 | 14 | 4 | 11 | 1 | 9 | 2 | 217 | 1 | 1.72 | 6.91 | 0.62 | 35.0 | 5.1 | 0.75 | .224 | 2.18 | 4.99 |
| 6 |  | A. Vesia | 11.80 | 66.1 | 2024 |  LAD | 67 | 5 | 4 | .556 | 0 | 1.76 | 87 | 0 | 0 | 5 | 33 | 13 | 19 | 7 | 33 | 1 | 10 | 3 | 263 | 2 | 4.48 | 2.64 | 0.95 | 33.1 | 12.5 | 0.99 | .193 | 2.58 | 4.48 |
| 7 |  | K. Bubic | 11.57 | 30.1 | 2024 |  KCR | 27 | 1 | 1 | .500 | 0 | 2.67 | 39 | 0 | 0 | 1 | 26 | 9 | 12 | 2 | 5 | 0 | 7 | 3 | 121 | 1 | 1.48 | 7.80 | 0.59 | 32.2 | 4.1 | 1.02 | .320 | 3.56 | 7.71 |
| 8 |  | D. Young | 11.47 | 37.2 | 2024 |  NYM | 42 | 4 | 1 | .800 | 0 | 4.54 | 48 | 0 | 0 | 0 | 29 | 19 | 22 | 3 | 18 | 7 | 13 | 1 | 165 | 5 | 4.30 | 2.67 | 0.72 | 29.1 | 10.9 | 1.25 | .292 | 5.26 | 6.93 |
| 9 |  | D. Lee | 11.46 | 59.2 | 2024 |  ATL | 52 | 4 | 2 | .667 | 0 | 2.11 | 76 | 0 | 0 | 0 | 49 | 14 | 19 | 7 | 17 | 0 | 8 | 4 | 240 | 0 | 2.56 | 4.47 | 1.06 | 31.7 | 7.1 | 1.11 | .300 | 2.87 | 7.39 |
| 10 |  | M. Strahm | 11.35 | 62.2 | 2024 |  PHI | 66 | 6 | 2 | .750 | 0 | 1.87 | 79 | 0 | 0 | 3 | 36 | 13 | 14 | 4 | 11 | 6 | 10 | 1 | 237 | 2 | 1.58 | 7.18 | 0.57 | 33.3 | 4.6 | 0.75 | .234 | 2.01 | 5.17 |
| 11 |  | R. Garcia | 11.31 | 59.2 | 2024 |  WSH | 72 | 3 | 6 | .333 | 0 | 4.22 | 75 | 0 | 0 | 0 | 55 | 28 | 34 | 4 | 16 | 1 | 6 | 1 | 251 | 4 | 2.41 | 4.69 | 0.60 | 29.9 | 6.4 | 1.19 | .329 | 5.13 | 8.30 |
| 12 | | J. Diekman | 11.25 | 32.0 | 2024 | NYM | 43 | 2 | 3 | .400 | 0 | 5.63 | 40 | 0 | 0 | 4 | 23 | 20 | 24 | 7 | 24 | 4 | 10 | 0 | 145 | 2 | 6.75 | 1.67 | 1.97 | 27.6 | 16.6 | 1.47 | .229 | 6.75 | 6.47 |
| 13 | | A. Bummer | 11.22 | 55.1 | 2024 | ATL | 56 | 4 | 3 | .571 | 0 | 3.58 | 69 | 0 | 0 | 0 | 61 | 22 | 24 | 2 | 18 | 2 | 13 | 2 | 244 | 2 | 2.93 | 3.83 | 0.33 | 28.3 | 7.4 | 1.43 | .386 | 3.90 | 9.92 |
| 14 | | A. Chafin | 11.18 | 56.1 | 2024 | TOT | 62 | 4 | 3 | .571 | 0 | 3.51 | 70 | 0 | 0 | 1 | 52 | 22 | 26 | 5 | 31 | 1 | 13 | 4 | 246 | 7 | 4.95 | 2.26 | 0.80 | 28.5 | 12.6 | 1.47 | .338 | 4.15 | 8.31 |
| 15 | | C. Ferguson | 11.10 | 54.1 | 2024 | TOT | 62 | 1 | 4 | .200 | 0 | 4.64 | 67 | 0 | 0 | 1 | 56 | 28 | 34 | 6 | 25 | 4 | 19 | 1 | 249 | 3 | 4.14 | 2.68 | 0.99 | 26.9 | 10.0 | 1.49 | .340 | 5.63 | 9.28 |
| 16 |  | K. Akin | 11.10 | 78.2 | 2024 |  BAL | 66 | 3 | 1 | .750 | 0 | 3.32 | 97 | 0 | 0 | 1 | 55 | 29 | 31 | 9 | 19 | 2 | 21 | 1 | 313 | 4 | 2.17 | 5.11 | 1.03 | 31.0 | 6.1 | 0.94 | .247 | 3.55 | 6.29 |
| 17 | | G. Soto | 11.04 | 53.0 | 2024 | TOT | 66 | 3 | 5 | .375 | 0 | 4.42 | 65 | 0 | 0 | 2 | 56 | 26 | 30 | 4 | 27 | 8 | 18 | 3 | 244 | 4 | 4.58 | 2.41 | 0.68 | 26.6 | 11.1 | 1.57 | .371 | 5.09 | 9.51 |
| 18 |  | B. King | 10.94 | 26.1 | 2024 | HOU | 28 | 1 | 0 | 1.000 | 0 | 2.39 | 32 | 0 | 0 | 0 | 20 | 7 | 7 | 1 | 10 | 3 | 7 | 0 | 109 | 0 | 3.42 | 3.20 | 0.34 | 29.4 | 9.2 | 1.14 | .302 | 2.39 | 6.84 |
| 19 | | B. Burke | 10.91 | 33.0 | 2024 | TOT | 33 | 2 | 0 | 1.000 | 0 | 5.18 | 40 | 0 | 0 | 0 | 34 | 19 | 19 | 4 | 16 | 2 | 9 | 2 | 148 | 0 | 4.36 | 2.50 | 1.09 | 27.0 | 10.8 | 1.52 | .349 | 5.18 | 9.27 |
| 20 |  | G. Cleavinger | 10.65 | 60.0 | 2024 |  TBR | 68 | 7 | 5 | .583 | 0 | 3.75 | 71 | 0 | 0 | 6 | 52 | 25 | 29 | 6 | 31 | 7 | 15 | 0 | 266 | 2 | 4.65 | 2.29 | 0.90 | 26.7 | 11.7 | 1.38 | .305 | 4.35 | 7.80 |
| 21 | | T. Scott | 10.50 | 72.0 | 2024 | TOT | 72 | 9 | 6 | .600 | 0 | 1.75 | 84 | 0 | 0 | 22 | 45 | 14 | 20 | 3 | 36 | 1 | 41 | 4 | 294 | 0 | 4.50 | 2.33 | 0.38 | 28.6 | 12.2 | 1.13 | .247 | 2.50 | 5.63 |
| 22 |  | C. Thielbar | 10.08 | 47.1 | 2024 |  MIN | 59 | 2 | 4 | .333 | 0 | 5.32 | 53 | 0 | 0 | 3 | 50 | 28 | 33 | 6 | 24 | 0 | 18 | 2 | 216 | 2 | 4.56 | 2.21 | 1.14 | 24.5 | 11.1 | 1.56 | .331 | 6.27 | 9.51 |
| 23 | | A. Morejon | 10.04 | 63.2 | 2024 |  SDP | 60 | 3 | 2 | .600 | 0 | 2.83 | 71 | 0 | 0 | 2 | 63 | 20 | 24 | 4 | 21 | 1 | 12 | 2 | 272 | 7 | 2.97 | 3.38 | 0.57 | 26.1 | 7.7 | 1.32 | .337 | 3.39 | 8.91 |
| 24 | | Y. Matsui | 9.91 | 62.2 | 2024 | SDP | 64 | 4 | 2 | .667 | 0 | 3.73 | 69 | 0 | 0 | 0 | 46 | 26 | 27 | 8 | 27 | 0 | 14 | 4 | 257 | 8 | 3.88 | 2.56 | 1.15 | 26.8 | 10.5 | 1.16 | .248 | 3.88 | 6.61 |
| 25 |  | J. Wilson | 9.84 | 46.2 | 2024 |  CIN | 60 | 1 | 5 | .167 | 0 | 5.59 | 51 | 0 | 0 | 2 | 55 | 29 | 30 | 10 | 13 | 2 | 15 | 1 | 209 | 3 | 2.51 | 3.92 | 1.93 | 24.4 | 6.2 | 1.46 | .338 | 5.79 | 10.61 |
StatMuse has game-level data for K/9 and innings pitched going back to the 1901 season.
Some of the information used here was obtained free of charge from Retrosheet.
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