In the previous post, I calculated conference strength for the offenses of the 11 NCAA FBS conferences and the three independent schools. Now I want to turn my attention to the defense. In order to do so, I will have to calculate the defensive productivity of each conference, and it is done similarly as for the offensive side of the ball, with one big exception. On the defensive side of the ball, the lower the number the better the defense. In other words the more defenses stop their opponents from scoring (and on field actions that lead to their opponent scoring) the better the overall defense. Thus better defenses have smaller numbers overall.
Given that better defenses have smaller numbers overall, worse defenses have higher numbers, so a conference with a defense of 1.500 is 50% as productive as the most productive defense.
So with that in mind, here are the conference strengths as of October 30, 2010.
| Conference | Defense |
| Big East |
| 1.000 |
| Independent | 1.204 |
| Big 10 |
| 1.215 |
| SEC |
| 1.275 |
| ACC |
| 1.279 |
| Big 12 |
| 1.343 |
| Pac 10 |
| 1.382 |
| WAC |
| 1.463 |
| Mountain West | 1.483 |
| Sun Belt |
| 1.494 |
| CUSA |
| 1.589 |
| Mid American | 1.591 |