I agree that the defense has certainly struggled the last couple of years. However, do not blame the defense for all the problems.
For those of you that have attended ISU games over the last couple seasons, you know that the defense is usually on the field 75% of the game. The Offense would routinely go 3 and out. The defense never had much time to rest. Not to mention, every time the defense made a nice stop, they only got to rest for 4 plays. Not only is that physically tough, it's mentally devistating. That plus no depth, equals struggling defensive play.
We will get better!