I believe that ESPN would prefer to have a matchup like 8-win BYU again 9-win Navy or SMU if they could get it. That would maximize TV viewership. They would then ship 7-6 Hawaii off to one of the MWC's lesser bowls against another 6 or 7-win team.
But, if Hawaii finishes at 8-5 or BYU finishes at 7-5, the BYU v. Hawaii matchup will be good enough for the bowl game.