If you are going to play in a weak conference, you have to go undefeated. Period.
If you manage to accomplish that, and have 2 or 3 good out of conference wins, then you have a chance to get in. Case in point: look at Notre Dame (essentially a Big 10 team for our discussion purposes).
A win over Florida would have certainly helped if they could get it. But they would need another good out of conference win to go with it. The last two years they played a home and home with Oklahoma, which helps considerably. But they lost BOTH of those games. They only help if you win them.
This year they don't have that 2nd good out of conference game at all for whatever reason. Which leaves the lingering thought that if they had played an Oklahoma team again this year they probably would have lost again.