Roy Oswalt had a 143-82 record with an ERA of 3.24 and 1,593 strikeouts in 303 appearances for the Astros in his career.
| NAME | SEASON | TM | G | W | L | W% | GS | ERA | 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 |  | R. Oswalt | 2001 |  HOU | 28 | 14 | 3 | .824 | 20 | 2.73 | 144 | 3 | 1 | 0 | 141.2 | 126 | 43 | 48 | 13 | 24 | 6 | 4 | 2 | 575 | 0 | 9.15 | 1.52 | 6.00 | 0.83 | 25.0 | 4.2 | 1.06 | .291 | 3.05 | 60 | 2.84 | 64 | 8.00 | 25.1 |
| 2 | | R. Oswalt | 2002 | HOU | 35 | 19 | 9 | .679 | 34 | 3.01 | 208 | 0 | 0 | 0 | 233.0 | 215 | 78 | 86 | 17 | 62 | 5 | 0 | 4 | 956 | 3 | 8.03 | 2.39 | 3.35 | 0.66 | 21.8 | 6.5 | 1.19 | .298 | 3.32 | 71 | 2.98 | 70 | 8.30 | 32.2 |
| 3 | | R. Oswalt | 2003 | HOU | 21 | 10 | 5 | .667 | 21 | 2.97 | 108 | 0 | 0 | 0 | 127.1 | 116 | 42 | 48 | 15 | 29 | 5 | 0 | 0 | 514 | 1 | 7.63 | 2.05 | 3.72 | 1.06 | 21.0 | 5.6 | 1.14 | .283 | 3.39 | 68 | 3.66 | 84 | 8.20 | 10.1 |
| 4 | | R. Oswalt | 2004 | HOU | 36 | 20 | 10 | .667 | 35 | 3.49 | 206 | 2 | 2 | 0 | 237.0 | 233 | 92 | 100 | 17 | 62 | 11 | 0 | 5 | 983 | 5 | 7.82 | 2.35 | 3.32 | 0.65 | 21.0 | 6.3 | 1.24 | .314 | 3.80 | 80 | 3.16 | 71 | 8.85 | 33.6 |
| 5 | | R. Oswalt | 2005 | HOU | 35 | 20 | 12 | .625 | 35 | 2.94 | 184 | 4 | 1 | 0 | 241.2 | 243 | 79 | 85 | 18 | 48 | 8 | 0 | 3 | 1,002 | 5 | 6.85 | 1.79 | 3.83 | 0.67 | 18.4 | 4.8 | 1.20 | .302 | 3.17 | 70 | 3.15 | 73 | 9.05 | 30.4 |
| 6 | | R. Oswalt | 2006 | HOU | 33 | 15 | 8 | .652 | 32 | 2.98 | 166 | 2 | 0 | 0 | 220.2 | 220 | 73 | 76 | 18 | 38 | 6 | 1 | 4 | 896 | 1 | 6.77 | 1.55 | 4.37 | 0.73 | 18.5 | 4.2 | 1.17 | .302 | 3.10 | 67 | 3.29 | 72 | 8.97 | 31.1 |
| 7 | | R. Oswalt | 2007 | HOU | 33 | 14 | 7 | .667 | 32 | 3.18 | 154 | 1 | 0 | 0 | 212.0 | 221 | 75 | 80 | 14 | 60 | 7 | 0 | 6 | 910 | 1 | 6.54 | 2.55 | 2.57 | 0.59 | 16.9 | 6.6 | 1.33 | .307 | 3.40 | 73 | 3.58 | 79 | 9.38 | 22.2 |
| 8 | | R. Oswalt | 2008 | HOU | 32 | 17 | 10 | .630 | 32 | 3.54 | 165 | 3 | 2 | 0 | 208.2 | 199 | 82 | 89 | 23 | 47 | 10 | 0 | 2 | 862 | 1 | 7.12 | 2.03 | 3.51 | 0.99 | 19.1 | 5.5 | 1.18 | .285 | 3.84 | 84 | 3.79 | 87 | 8.58 | 13 |
| 9 | | R. Oswalt | 2009 | HOU | 30 | 8 | 6 | .571 | 30 | 4.12 | 138 | 3 | 0 | 0 | 181.1 | 183 | 83 | 83 | 19 | 42 | 8 | 0 | 4 | 757 | 4 | 6.85 | 2.08 | 3.29 | 0.94 | 18.2 | 5.5 | 1.24 | .298 | 4.12 | 100 | 3.75 | 88 | 9.08 | 10.4 |
| 10 | | R. Oswalt | 2010 | HOU | 20 | 6 | 12 | .333 | 20 | 3.42 | 120 | 1 | 1 | 0 | 129.0 | 109 | 49 | 52 | 13 | 34 | 2 | 0 | 2 | 521 | 2 | 8.37 | 2.37 | 3.53 | 0.91 | 23.0 | 6.5 | 1.11 | .273 | 3.63 | 86 | 3.36 | 83 | 7.60 | 9.6 |
| Total | 303 | 143 | 82 | .636 | 291 | 3.24 | 1,593 | 19 | 7 | 0 | 1932.1 | 1,865 | 696 | 747 | 167 | 446 | 68 | 5 | 32 | 7,976 | 23 | 7.42 | 2.08 | 3.57 | 0.78 | 20.0 | 5.6 | 1.20 | .298 | 3.48 | 76 | 3.35 | 77 | 8.69 | 217.7 |
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