Regular Season
| Season | TM | G | GS | W | L | ERA | SO | CG | SHO | SV | IP | H | ER | R | HR | BB | HBP | WHIP |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1978 | TEX | 3 | 1 | 1 | 0 | 4.15 | 8 | 0 | 0 | 0 | 8.2 | 11 | 4 | 4 | 0 | 1 | 0 | 1.38 |
| 1979 | TEX | 20 | 6 | 4 | 4 | 4.04 | 58 | 1 | 0 | 0 | 78.0 | 50 | 35 | 36 | 5 | 30 | 5 | 1.03 |
| 1980 | TEX | 53 | 2 | 13 | 4 | 2.63 | 104 | 0 | 0 | 8 | 109.2 | 98 | 32 | 37 | 4 | 50 | 2 | 1.35 |
| 1981 | TEX | 22 | 22 | 9 | 9 | 3.64 | 98 | 6 | 2 | 0 | 146.0 | 115 | 59 | 67 | 12 | 57 | 6 | 1.18 |
| 1982 | TEX | 56 | 1 | 10 | 8 | 3.44 | 61 | 0 | 0 | 7 | 89.0 | 95 | 34 | 38 | 6 | 37 | 2 | 1.48 |
| 1983 | TEX | 28 | 26 | 8 | 13 | 3.49 | 92 | 9 | 2 | 0 | 183.0 | 175 | 71 | 86 | 9 | 62 | 3 | 1.30 |
| 1984 | TEX | 35 | 32 | 8 | 12 | 3.94 | 123 | 5 | 1 | 0 | 223.2 | 249 | 98 | 110 | 19 | 54 | 4 | 1.35 |
| 1985 | MIL | 39 | 29 | 8 | 18 | 3.80 | 125 | 11 | 1 | 2 | 217.2 | 212 | 92 | 112 | 34 | 65 | 4 | 1.27 |
| 1986 | MIL | 27 | 14 | 6 | 8 | 3.52 | 80 | 5 | 1 | 0 | 130.1 | 120 | 51 | 62 | 13 | 35 | 3 | 1.19 |
| 1986 | HOU | 12 | 8 | 5 | 2 | 2.32 | 40 | 1 | 0 | 0 | 54.1 | 50 | 14 | 19 | 3 | 9 | 0 | 1.09 |
| 1986 | TOT | 39 | 22 | 11 | 10 | 3.17 | 120 | 6 | 1 | 0 | 184.2 | 170 | 65 | 81 | 16 | 44 | 3 | 1.16 |
| 1987 | HOU | 33 | 30 | 9 | 10 | 3.59 | 134 | 3 | 1 | 0 | 195.2 | 184 | 78 | 87 | 17 | 69 | 5 | 1.29 |
| 1988 | HOU | 44 | 20 | 8 | 13 | 3.84 | 129 | 3 | 0 | 3 | 192.0 | 189 | 82 | 86 | 20 | 48 | 7 | 1.23 |
| 1989 | HOU | 68 | 0 | 11 | 4 | 2.36 | 104 | 0 | 0 | 7 | 122.0 | 92 | 32 | 34 | 8 | 33 | 2 | 1.02 |
| 1990 | HOU | 48 | 17 | 11 | 4 | 2.21 | 109 | 3 | 0 | 2 | 162.2 | 136 | 40 | 42 | 11 | 31 | 4 | 1.03 |
| 1991 | BOS | 12 | 12 | 3 | 6 | 5.16 | 42 | 0 | 0 | 0 | 68.0 | 71 | 39 | 39 | 15 | 15 | 4 | 1.26 |
| 1992 | BOS | 51 | 15 | 9 | 9 | 3.96 | 124 | 2 | 0 | 3 | 161.1 | 159 | 71 | 76 | 11 | 53 | 5 | 1.31 |
| 1993 | BOS | 34 | 34 | 15 | 11 | 3.26 | 130 | 2 | 1 | 0 | 229.1 | 196 | 83 | 93 | 31 | 49 | 3 | 1.07 |
| 1994 | BOS | 13 | 13 | 7 | 5 | 6.30 | 54 | 0 | 0 | 0 | 75.2 | 101 | 53 | 54 | 13 | 24 | 1 | 1.65 |
| 1995 | TOR | 13 | 11 | 1 | 8 | 7.62 | 36 | 1 | 0 | 0 | 65.0 | 91 | 55 | 60 | 13 | 24 | 3 | 1.77 |
| 1995 | TEX | 7 | 4 | 2 | 2 | 7.15 | 22 | 0 | 0 | 0 | 34.0 | 40 | 27 | 27 | 12 | 7 | 1 | 1.38 |
| 1995 | TOT | 20 | 15 | 3 | 10 | 7.45 | 58 | 1 | 0 | 0 | 99.0 | 131 | 82 | 87 | 25 | 31 | 4 | 1.64 |
| 1996 | PIT | 19 | 19 | 7 | 9 | 3.02 | 69 | 0 | 0 | 0 | 122.1 | 117 | 41 | 48 | 9 | 16 | 6 | 1.09 |
| 1996 | HOU | 15 | 6 | 3 | 2 | 5.95 | 27 | 0 | 0 | 0 | 42.1 | 43 | 28 | 31 | 7 | 11 | 6 | 1.28 |
| 1996 | TOT | 34 | 25 | 10 | 11 | 3.77 | 96 | 0 | 0 | 0 | 164.2 | 160 | 69 | 79 | 16 | 27 | 12 | 1.14 |
| 1997 | CWS | 21 | 17 | 4 | 8 | 4.13 | 62 | 1 | 0 | 0 | 113.1 | 130 | 52 | 60 | 21 | 31 | 1 | 1.42 |
| 1997 | SFG | 10 | 7 | 1 | 3 | 4.91 | 30 | 0 | 0 | 0 | 44.0 | 51 | 24 | 26 | 5 | 14 | 1 | 1.48 |
| 1997 | TOT | 31 | 24 | 5 | 11 | 4.35 | 92 | 1 | 0 | 0 | 157.1 | 181 | 76 | 86 | 26 | 45 | 2 | 1.44 |
| 1998 | SFG | 33 | 25 | 8 | 10 | 5.51 | 81 | 0 | 0 | 0 | 148.2 | 176 | 91 | 97 | 23 | 49 | 3 | 1.51 |
| Career | 716 | 371 | 171 | 182 | 3.84 | 1,942 | 53 | 9 | 32 | 3016.2 | 2,951 | 1,286 | 1,431 | 321 | 874 | 81 | 1.27 |
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