BYU is pretty consistent in having a let down after a big victory or an emotional victory.

A few examples:

1990- BYU beats #1 Miami. The next week they play Washington St, are favored to win easily but fall behind by several touchdowns at halftime. They did come back and win the game by scoring 35 points I believe in the 2nd half.

2009- BYU begins the season with an underdog victory over the #3 ranked Oklahoma Sooners. BYU jumps up in the rankings, and 2 weeks later for the home opener, plays a below average Florida St team they were predicted to beat by double digits, but play the game uninspired and lose big time.

This season, an emotional win against utah, they then are predicted to be #4 in the playoff rankings with a first round bye, yet lose to a below average team in Kansas the following week at home.

Also look at last week vs ASU, why does it take a player having to give an emotional rant at halftime to fire the team up?

This happens to many of other teams as well, but NOT to Championship caliber teams.

Why does this happen?
Coaching? Their could be a little truth here, since part of a coaches job is to motivate a team. But I think ultimately it lies with the players. Take pride is playing as hard as you can every week because you want to play at your highest ability. Take pride in being better than the person you are lined up against across the line of scrimmage.

Next season BYU will win a big game they were not favored to win, or come away with an emotional victory, but watch what happens the next week.
Sad to see it, but it's really predictable at this point.