Until the late 3rd quarter, BYU was usually only bringing three on most defensive plays. D line technique was pretty poor, too - no one was swimming and stunts weren't being called. BYU's D linemen were simply bull-rushing and getting practically no penetration. Perhaps this was intentional (using linemen to try to simply fill lanes and contain plays) but it practically ceded the LOS to Houston.

Late in the 3rd quarter, BYU's D line came alive. They started bringing 4 on most plays (frequently using 4 down linemen) and began stunting instead of simply bull-rushing (Dawe got a big sack on coming free on a stunt). As soon as that change was made, Houston's QB began having issues completing passes (especially with downfield passes that Houston had previously been completing for "chunk" yardage). I think the changes on the defensive LOS were at least as important as the change in coverage.