Simple, physical football designed to pick up four yards at a time. Their OL did start to win the battle halfway through the third quarter, but part of that was Utah backing its safeties off the LOS because the secondary had been burned in the first half and they had a two touchdown lead.
What worries me about BYU v Michigan is Bronco is going to see the film and think the BYU will match Michigan physically and keep the gameplan conservative believing his veteran offense will pull it out in the fourth quarter. The same pattern has failed at ND a couple of times, failed at Wisconsin, failed at Virginia, failed at Texas in 2011 (classic example). His team doesn't have a long history of pulling through in the second half on the road against big name opponents.