mistakes. BSU made enough mistakes last games (untimely penalties, unforced fumble, ill advised pass that led to int, dropped passes, QB missing wide open receivers without any pressure) that BYU was able to stay in the game. Still didn't get enough pressure on the QB or negative plays for my liking. Teams that avoid mistakes blow them out.
Hawaii was a great game. They pressured the QB, forced errant throws, made negative plays, etc...
They are adequate and not the reason the team is losing, but to say they have "played great" is extreme hyperbole.