vs FBS opponents only
111th in pass efficiency defense
123rd in comp% allowed
88th in passes defended per game
120th in sacks per game
123rd in tackles for loss per game
82nd in 3rd down conversions
99th in 4th down conversions
BYU's only saving grace on defense is they are 14th best in limiting red zone TDs, as a percentage of all red zone possessions (48%), and that's what makes them look a lot better than they really are. They have played a lot of poor passing offenses and still stink in their defensive stats. They have struggled to get off the field. They have not done a good enough job.
Sure, the injuries are a major factor, but that's not the whole story.