BYU struggled some in their last two victories. They were one play from losing to a decimated USC team. I think that is the reason for the line.
However, looking at the two teams, I have every reason to believe BYU will win going away. They may be ticked that they are stuck in a worthless bowl game, but they really want to end the season ranked in the top-ten. I think the motivation in the locker room is “respect.” The coaches are harping on the lack of respect they are getting and that they need to prove to the nation that they are indeed a top-ten team. I’m not sure if it will work.