Ohio State has already lost its bowl game. Not a top 4 team.
1) Bama
2) Texas
T3) Georgia
T3) Michigan
Michigan had played 3 teams that were good enough to be in the next to last rankings and was undefeated. (Not going by what an opponent was ranked when Michigan played them, but how they ranked in the end.) Georgia also played 3 of those teams with just 1 loss: by 3 points to Bama. Texas played 4 of those teams with just 1 loss. Bama played a whopping 5 of those teams with just 1 loss.
Want to know why Washington and FSU were undefeated (before FSU's thunderfumping by Georgia)? Because they each played only 2 of the teams ranked in the end (Washington playing Oregon twice, though, so 3 games against final ranked teams). Call me unimpressed.
From a pure put up or shut up perspective against a tough strength of schedule, Bama and Texas stand out.