If BYU run the month of Sep, they vault into the top 10. As other teams pick up losses, the damage for a loss becomes slightly less later in the season.
One other thing, for statisticians, Utah's schedule may very well end up on top...but from a perception standpoint what BYU is doing will carry more weight. Utah is playing their conference. Everyone does it. BYU is going around the country picking fights.
In the end, 9-3 has both teams in the top 25...and possibly meeting in Vegas. Now that would be an epic Vegas bowl...