That's true, but there's a reason why red zone efficiency is emphasized.

In the red zone the field obviously gets smaller and the defense is able to get a little tighter. Therefor the offense has to be more efficient. If a team is not good at moving the ball and putting points on the board while in the red zone, then it logically follows that in order to remain a high scoring team, they must have more explosive plays from outside the zone. Notre Dame had some but was not great at those kinds of plays with Ian Book at QB.