But freshman quarterback Tanner Mangum came on to throw the game - winning Hail Mary , and he has been stellar ever since .
BYU lost its starting quarterback , Taysom Hill , to a season - ending foot injury in its season - opener against Nebraska .
Freshman quarterback Tanner Mangum came on to throw the game - winning Hail Mary , and he has been stellar ever since .
BYU lost its starting quarterback , Taysom Hill , to a season - ending foot injury in its season - opener against Nebraska .