Utah also beat a Washington team the clobbered BYU. We don't know exactly how good Utah is, but there's room to believe that their loss to USC was a fluke.

The "we don't know how good they are" argument isn't very compelling; it can be made about almost any team outside of the B1G and SEC. We also don't really know how good OU, Clemson, and Baylor are. Those teams are from conferences that are surprisingly weak this year (ACC) or play flag football defense (OU, Baylor) and haven't really played anyone. But all those teams are 12-0 or 11-1—and that's not easy for anyone to do, regardless of how "weak" the schedule is.