Here's what I don't understand. If you know the other teams strategy is going to be to get the ball out quickly because their o-line isn't a match for your d-line why not play everyone up and make the quarterback hold the ball a little longer? Why not make them beat you deep once?
Take Northwestern for example. We all know what they're going to try and do. But why not play the corners up and make them prove they're even able to throw the ball downfield without one of our safeties getting to it. But by allowing them to run 5 yard slants/outs all game you effectively eliminate the two best units on Iowa's defense (d-line and safeties)
Simply put, because we're better at what we do defensively than they are at what they do offensively. IMO. Indiana did the same thing and we held them way below their scoring average and had multiple balls that could have been intercepted.