You see this quite often in sports. When teams have their back against the wall, it is often said they are like cornered animals--dangerous. Totally agree. We've all seen it. I expect Utah to come out fired up and to throw a proverbial punch at BYU early.
But...more often than not, teams with their backs against the wall are in that position because they have fatal flaws, whether in the locker room, or attitude, or ability. They often crumble fast once the better team absorbs the opening blow, settles down, and plays to their potential.
You see it basketball all the time in the playoffs. A team is down 3-1, comes out hot, takes a 15 point lead, and then as soon as the other team makes a run, everything fall apart. These often turn into blowouts, despite how the game started. You see it similarly in football all the time. An hyped up underdog team strikes early, maybe takes a 10-0 lead. And then by early in the 3rd the better team takes the lead, and by the 4th it is a boat race.
We can all find exceptions, but if Utah is really a mess in the lockerroom and the team chemistry is low, it is very possible that they'll fall apart when things get tough for them. These are all just rumors, but there have been a lot of them. Where there is smoke, there is probably fire.