Regular season and playoffs
| Year | Team | Games | Att | Cmp | Cmp% | Pass Yds | Pass TD | INT | Sacks | Y/A | Rating |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 1979 | SF | 16 | 23 | 13 | 56.5 | 96 | 1 | 0 | 0 | 4.2 | 81.1 |
| 1980 | SF | 15 | 273 | 176 | 64.5 | 1795 | 15 | 9 | 15 | 6.6 | 87.8 |
| 1981 | SF | 19 | 576 | 367 | 63.7 | 4312 | 25 | 16 | 33 | 7.5 | 89.3 |
| 1982 | SF | 9 | 346 | 213 | 61.6 | 2613 | 17 | 11 | 20 | 7.6 | 88.0 |
| 1983 | SF | 18 | 594 | 377 | 63.5 | 4458 | 30 | 14 | 35 | 7.5 | 93.3 |
| 1984 | SF | 19 | 540 | 346 | 64.1 | 4503 | 35 | 15 | 30 | 8.3 | 100.3 |
| 1985 | SF | 16 | 541 | 329 | 60.8 | 3949 | 27 | 14 | 39 | 7.3 | 89.0 |
| 1986 | SF | 9 | 322 | 199 | 61.8 | 2334 | 8 | 11 | 12 | 7.2 | 77.8 |
| 1987 | SF | 14 | 424 | 278 | 65.6 | 3163 | 31 | 14 | 26 | 7.5 | 98.4 |
| 1988 | SF | 17 | 487 | 294 | 60.4 | 3804 | 26 | 11 | 40 | 7.8 | 93.3 |
| 1989 | SF | 16 | 469 | 336 | 71.6 | 4321 | 37 | 8 | 34 | 9.2 | 119.4 |
| 1990 | SF | 17 | 577 | 361 | 62.6 | 4408 | 29 | 17 | 34 | 7.6 | 90.5 |
| 1992 | SF | 1 | 21 | 15 | 71.4 | 126 | 2 | 0 | 1 | 6.0 | 118.4 |
| 1993 | KC | 14 | 402 | 240 | 59.7 | 2844 | 17 | 10 | 20 | 7.1 | 85.0 |
| 1994 | KC | 15 | 530 | 325 | 61.3 | 3597 | 18 | 10 | 19 | 6.8 | 84.9 |