Though I doubt it will happen.
BYU's Defense will already be keeping these games close (though LSU may pull away from an exhausted Cougar D in the 4th quarter). If BYU can establish a decent run game against these teams, I think they will win. Not only those games, but every game on their schedule.
Right now the Cougars feature a great defense that forces a ton of turnovers, what is likely to be a somewhat above average passing game, and a weak rushing attack. If BYU can get a decent push against LSU and Wisconsin defenders, that means BYU's run game will be in the good to very good range and will upgrade the passing game to a similar level.
A top 15 scoring defense and a top 30 scoring offense is a very powerful combination. Last year only 5 teams managed that. They finished the regular season ranked 1,2,3,4, and 6.
I don't honestly see how that could possibly happen though. I predict something more along the lines of a 10th ranked defense and 50th ranked offense. That will be enough for a 10 or 11 win regular season and a top 25 ranking.