The Beavers took themselves out of the game right off the bat, failing to stop the Sun Devils on the opening drive and falling behind early. The Beavers could not answer however, and despite two interceptions of Taylor Kelly, the offense could do nothing with it and Arizona State would score again moving the score to 13-0. The Beavs got the ball back and failed to do anything with it, punting it away after another failed drive. The Sun Devils would mount up for another drive after that.
The Beaver defense had done better than expected, but they were getting trampled on the drive. They would eventually force a stop though, forcing two incompletions, and a short loss on a screen pass. With the punt, the Beavers had a chance to start another drive in order to make it a one score game. This never came to fruition however as Brandin Cooks muffed the punt and was immediately swarmed by the Sun Devil special team unit.
It seemed at this moment that the Beavers would not be able to overcome ASU. The Sun Devils are a quality team and the Beavers had offered up too many chances for them to take control. When the best player on the team is making awful mistakes it makes it difficult to overcome. Arizona State went on to go up 20-0 and the Beavs could only get back to within 10 later.
There were other moments later which also affected momentum, but the damage had already been done. Mannion's pick-six comes to mind, the drive at the end of the first half that ended in a field goal at the 5, or the blocked field goal and penalty that left the game a two-score difference. All these affected the game, but for how the Beavs had been playing, a three-score game was just too much to overcome, and that muffed punt made it too easy for the Sun Devils to take control.