I agree with your post, except the sack discrepancy does not account for BYU taking off most of the 3rd and 4 to quarters because of the score. Even when the starters and 2s have been in later in the game, they have rarely played with anything more than the 3 man rush and have just tried to finish games without injuries. A couple games we have seen them go hard in the 4th, when the other team started to make a run or score, but after they got a few quick 3 and outs or turn over, it went right back to the vanilla bend but not break. If BYU had played all out, every quarter of every game, how many more sacks would they have? Heck, Tonga sat out against Houston, one of the better games, and the D line still dominated. It will definitely come down to longer play, but the sack line does not equate to their having a D line or defense anywhere close to BYU.