I think there's validity to both sides at the end of the season, of teams ranked in the top 25, for arguments sake, lets include CCG:
OSU has beaten: #21 Wisconsin and #10 MSU. Thay have lost to nobody
Auburn has beaten: #24 Texas A&M, #22 Georgia, #5 Missouri and #1 Alabama. They have lost to #15 LSU
Florida State has beaten: #13 Clemson and #20 Duke. They have lost to nobody.
Auburn is worse because of the loss, but better because of their wins.
FSU and OSU are worse because of their wins (similar, although FSU has a marginally worse SOS) and better because they are undefeated.
In the end, although I think Auburn deserves a shot at the BCS, I can understand why they could be left out. If I REALLY wanted to be sure an SEC school was in, I would have been rooting for Bama. It's an imperfect system that a 4 team playoff helps, but an 8 team playoff would. IMHO, be almost perfect.