BYU was already ranked #1 when they played their bowl game; they wouldn't have been voted as National Champions regardless of which bowl they played in if they hadn't already been at the top, unless everybody else above them lost, but, even during the regular season pollsters would boost other teams above BYU despite the Cougars continuing to win; it happened both with Nebraska, which lost in week 5, and later with South Carolina, which didn't even enter the polls until week 5/6 (AP/Coaches).