Personally, I believe the defense was average to start the year and has progressively gotten worse. At this point, they're worse than the offense. People talk about how they are giving up less PPG than most conference teams...well, with how bad the offense was earlier in the season, teams didn't NEED to score all that much to win. They get up by 2 TDs and they knew ISU couldn't come back on them, so they ran the ball and worked the clock.
Right now I think the D is flat out bad. The O is finally playing well enough to win some games and the D is a sieve. To me, it's shocking how little depth the LB group had. This staff had three years to find replacements for Knott and Klein. You'd think that at this point, the last games of Knott and Klein's season, there would be some guys waiting in the wings to replace them. That is not the case. So, they had to scramble Klein, forcing him to a new position for his last few games and he's spent them trying to do too much. Jeremiah George is a horrible LB. He consistently makes bad reads and misses tackles. You hardly ever see him make a solo tackle or even a good play. He's a liability and that says something that Miller can't see the field over him (or taking over for Knott and keeping George and Klein where they were). I'd rather have Taufoou then George and he wasn't that good. If next year's D is built around George and Miller at LB and Jensen, Woods, Scott and Irving on the DL, I am terrified of what that run D will be like. Maybe one of the worst BCS run defenses of the last 20 years.
So far what I see is some bad recruiting at LB and WR, where the talent seems to go downhill every year. The only difference between those two positions is that the staff lucked onto two all-conference LBs their first season. After that, the recruiting has been strikingly similar.