The Defense actually didnt play as bad as the score indicated. They had a lot of trouble corralling McSorley for sure, and he created issues with his extension of plays, but Penn St got a lot of points off of blind luck and terrible officiating. One touchdown was clearly not a catch in bounds as the WR was bobbling the ball, but they didnt overturn the original call. One touchdown was complete luck as Marshall had perfect position on a deep ball, bats the ball away, and it deflects sideways into the Penn St WR hands. Terrible luck on that.
One drive should have ended in a FG when a stop was made on 3rd down no where near a 1st down, but the tackler's hand got the facemask on the tackle. One TD drive should have ended on a 3rd down that was spotted poorly after a WR bobbled the ball and lost 3 yards, and they gave them a 1st down like he never bobbled it. Another TD drive came from 3 yards out after an INT that was clearly caused by the DB slamming into JuJu Smith way early, popping the ball in the air for the INT.
Penn St scored 28 points in a 5:28 span of the game, mostly off of the above flukey plays. Once that little run was over, USC shut them down, including shutting them out in the 4th Quarter when it mattered. I think in 4 drives in the 4th quarter they had like 14 total yards. So yeah, the 49 points looks awful, but it wasnt really as bad as it seems on paper.