If you stand there and watch the other team come out of the half and line up a receiver on a corner, throw to him four straight times to move down for a TD because it is an obvious mismatch, then replace that corner in the next defensive series with guys further down the depth chart to defend the receiver killing you, allowing the mismatch to give Purdue a second easy TD, before you finally figure out to put your one good corner on the receiver, you are pretty clueless as a coach. If you can't figure things out quickly, burn a freaking timeout to figure it out. I am amazed that Purdue's coaches were the first to notice that #5 is not capable of much... Iowa isn't good enough to gift rap two TDs.
On the offensive side of the ball, when Purdue lined a backer up on the line to overload one side to blitz, Iowa never made an adjustment, allowing a free run at the QB every time they did it. Maybe this was also a QB problem for not calling for an adjustment before the snap, but it killed a couple of Iowa drives.
The quality of Iowa's punter is the worst I have seen in decades of watching. There LOTS of better punters out there to recruit, so that is also on the coaches...
There were plenty of player failures that contributed to the loss, but failure to make adjustments, play calling, and recruiting failures also contributed...