The defense was NOT at fault for the 2015 Vegas Bowl. Did you even watch the game?
I guess you missed the goal line stand in the Boise St game (if we're picking out one off drives smh).
Try looking at the defensive stats for the past 15 yrs. Bronco's defenses are all better than Tuiaki's defenses. No one is saying Kalani is a bad coach and can't fix the defense only that he protected his buddy for far too long.
Try not to ignore actual stats.