Well, if the Iowa D isn't worn out, then 'splain this, smart guy: First 8 games Iowa gives up about 15 points per game. Last 3 games, Iowa gives up about 28 points a game...against Indiana, Minnesota, and Purdue.
And then everybody is running the ball against the Iowa D, and passing it, and pretty much having their way. The stats are there. So is the eye test. No pressure AT ALL on the QB. Every single FACT shouts TIRED DEFENSE.
So the facts would seem to suggest the OP is correct. Morehouse of The Gazette has said so, too. Anybody with eyes and a brain would say so. What will KF and PP do about it? That's what you should be worried about.