Two things.
1- 9 game conf schedule. While Auburn has 8 conf games and Oregon, Oregon has 9 games and Auburn. The week in, week out attrition is real. Plus, when you play 8 conf games you theoretically give your conference 6 more wins. That 8-4 ASU team that you beat now becomes a 9-3 ranked, really good ASU team that you beat. Even though ASU’s schedule got easier, yours got harder.
2- there has been no “top dog”. The ACC and Big 12 suuuck. But no one says anything because Oklahoma and Clemson have been good. If USC was going 12-0, the conference would be great again.