| Week | Rank | Rate | Record | SOS | Opponent | Score | Rank Then | Rank Now |
| 0 | 9 | 0.000 | (0,0) | 0.000 | --bye-- |
| 1 | 7 | 0.500 | (1,0) | -0.500 | Montana St | 59 to 13 | 518 | 33 |
| 2 | 663 | -1.985 | (2,0) | -2.985 | Oklahoma St | 69 to 3 | 690 | 161 |
| 3 | 39 | 1.727 | (3,0) | 0.727 | Northwestern | 34 to 14 | 115 | 48 |
| 4 | 40 | 1.674 | (4,0) | 0.674 | Oregon St | 41 to 7 | 228 | 152 |
| 5 | 20 | 2.109 | (5,0) | 1.109 | Penn St | 30 to 24 | 52 | 41 |
| 6 | 15 | 2.081 | (5,0) | 1.081 | --bye-- |
| 7 | 24 | 2.036 | (5,1) | 1.369 | Indiana | 20 to 30 | 4 | 1 |
| 8 | 18 | 2.027 | (6,1) | 1.312 | Rutgers | 56 to 10 | 114 | 75 |
| 9 | 16 | 2.068 | (7,1) | 1.318 | Wisconsin | 21 to 7 | 97 | 59 |
| 10 | 13 | 2.076 | (7,1) | 1.326 | --bye-- |
| 11 | 8 | 2.158 | (8,1) | 1.380 | Iowa | 18 to 16 | 45 | 27 |
| 12 | 9 | 2.207 | (9,1) | 1.407 | Minnesota | 42 to 13 | 52 | 44 |
| 13 | 5 | 2.314 | (10,1) | 1.495 | USC | 42 to 27 | 12 | 14 |
| 14 | 3 | 2.354 | (11,1) | 1.520 | Washington | 26 to 14 | 29 | 23 |
| 15 | 4 | 2.381 | (11,1) | 1.548 | --bye-- |
| 16 | 3 | 2.389 | (11,1) | 1.556 | --bye-- |
| 17 | 2 | 2.445 | (12,1) | 1.598 | James Madison | 51 to 34 | 24 | 26 |
| 18 | 2 | 2.474 | (12,1) | 1.628 | --bye-- |
| 19 | 2 | 2.520 | (13,1) | 1.663 | Texas Tech | 23 to 0 | 10 | 10 |
| 20 | | | | | Indiana | | | 1 |
| 21 | | | | | --bye-- |