If they can stop the run with their front line without much linebacker support, than running it over and over isn't going to yield a ton of benefit right away. Maybe eventually, you can tire out the front line causing more support from the linebackers and opening up certain things in the passing game.

Far too often I've seen BYU's run game very easily stopped without the defense having to make many adjustments to do it. To me that is fruitless running. When that happens you have to switch to the mindset of passing to open up the run.