UConn does this all the time in basketball. They go into someone else's gym and puts a run together. The first job of the away team is to silence the home crowd. BYU did that, and you're surprised UConn was cheering about it? C'mon, Man.
BYU went down the field and scored on their first possession, while overcoming more then a couple personal foul penalties. I though BYU played a little dirty, and I commend UConn for not retaliating, but BYU was literally pushing UConn all over the field. UConn got something going after they were down 14 and the crowd was in it (contrary to your assessment), but the score, the 2 early turnovers, and all the penalties (which severely disrupted the flow of the game) and that tends to diminish the effects of the crowd.
UConn didn't do anything for which fans could cheer up to that point. Start with the product, not the patrons.