| 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 | Missouri St | 73 to 13 | 518 | 102 |
| 2 | 155 | 0.508 | (2,0) | -0.492 | Ga Southern | 59 to 20 | 433 | 91 |
| 3 | 29 | 2.025 | (3,0) | 1.025 | Purdue | 33 to 17 | 84 | 111 |
| 4 | 15 | 2.185 | (4,0) | 1.185 | Michigan St | 45 to 31 | 52 | 89 |
| 5 | 24 | 1.954 | (4,1) | 1.354 | Illinois | 32 to 34 | 18 | 19 |
| 6 | 24 | 1.985 | (4,1) | 1.385 | --bye-- |
| 7 | 18 | 2.086 | (5,1) | 1.419 | Michigan | 31 to 13 | 34 | 18 |
| 8 | 21 | 1.981 | (5,2) | 1.553 | Notre Dame | 24 to 34 | 11 | 9 |
| 9 | 24 | 1.913 | (5,2) | 1.485 | --bye-- |
| 10 | 18 | 2.020 | (6,2) | 1.520 | Nebraska | 21 to 17 | 46 | 55 |
| 11 | 9 | 2.134 | (7,2) | 1.578 | Northwestern | 38 to 17 | 54 | 48 |
| 12 | 10 | 2.201 | (8,2) | 1.601 | Iowa | 26 to 21 | 49 | 27 |
| 13 | 12 | 2.074 | (8,3) | 1.619 | Oregon | 27 to 42 | 5 | 2 |
| 14 | 11 | 2.079 | (9,3) | 1.579 | UCLA | 29 to 10 | 85 | 84 |
| 15 | 12 | 2.096 | (9,3) | 1.596 | --bye-- |
| 16 | 12 | 2.098 | (9,3) | 1.598 | --bye-- |
| 17 | 12 | 2.105 | (9,3) | 1.605 | --bye-- |
| 18 | 12 | 2.124 | (9,3) | 1.624 | --bye-- |
| 19 | 14 | 2.032 | (9,4) | 1.648 | TCU | 27 to 30 | 21 | 21 |
| 20 | | | | | --bye-- |
| 21 | | | | | --bye-- |