As Trevor Matich pointed out yesterday, BYU's 3rd down conversion rate is terrible on offense. BYU also has a problem stopping teams on 3rd down as well.
Retzlaff's stats are decent at home, but he's averaging almost two INTs per game on the road.
On paper, BYU has no business being undefeated. I think a some bettors have been trying to cash in on that. Which has cost them. 🙂