Without Norm our defense has been average to bad! Miss seeing him on the sidelines....
Iowa's defensive problems have been a combination of issues, and it's not simply because Norm left. Iowa struggled defensively in that rough stretch from 05-07 and of course they were still developing in the early 2000s. But those teams had to deal with the same issues, Iowa has had to deal with in the 2010s.
First off, roster turnover. That means graduation, injury, transfer, early draft departure. Tyler Sash was a junior in 2010 and bounced for the NFL. A decision that seemed like the right thing at the time....he just made poor use of his opportunities.
From 2010-2012, Iowa was breaking in 3 young linebackers, who would go on to have a tremendous senior season. But prior to that, they struggled in different phases of the game. Oddly enough, it seems like this year's returning linebackers, who were essentially thrown to the wolves last year, are a bit further along in their development than Kirksey, Hitchens and Morris were their freshmen and sophomore years. How they pan out, though, remains to be seen. There's been several instances where we've had players hit a "developmental" wall after prior successful seasons.
Iowa has also had a lot of issues with the defensive line. Changes in scheme, changes in rotation, changes in depth. In 2011, Broderick Binns and Mike Daniels spearheads the defensive line, but they could never get any consistency out of the other spots. In 2012 they were gone, along with several other seniors, and that left a very young group to replace them. Steve Bigach and Joe Gaglione were the only two seniors at DL on the roster and the only junior that saw real playing time was Dominique Alvis, who battled injuries throughout his career. The rest were mostly untested sophomores and freshmen.
The backfield in 2011 and 2012 would have solid individual players, but wouldn't turn out to be a solid unit. Hyde occupied a spot in the backfield for 3 years. Tanner Miller held his own at times. Shaun Prater was solid for the most part in 2011, but he was gone after that. The rest of the guys that we saw shine in 2013 and 2014, if you want to make that claim, were underclassmen.
Iowa's issues boil down to poor timing. A mix of green youth, lack of depth and injuries kept Iowa defenses from gelling as well as some of the other defenses we've had in the past, despite having solid players at individual positions each year. We just haven't gotten seasons where we have a collection of talent up and down the starting lineup.
2008 and 2009 were essentially the same defense. 2010 is where the cracks began to show when we lost Spievey, Edds and Angerer, and had to deal with other injuries at linebacker.
Here's a look at the statistical rankings from the last 4 years:
2011-
Rush D: 62nd
Pass D: 58th
Scoring D: 46th
Pass Eff: 72nd
Turnovers: 85th
3rd down D: 99th
2012-
Rush D: 63rd
Pass D: 44th
Scoring D: 33rd
Pass Eff: 75th
Turnovers: 46th
3rd down D: 87th
2013-
Rush D: 19th
Pass D: 9th
Scoring D: 9th
Pass Eff: 17th
Turnovers: 60th
3rd down D: 31st
2014-
Rush D: 64th
Pass D: 7th (but second highest yds per completion in top 25, next to Pittsburgh)
Scoring D: 50th
Pass Eff: 34th
Turnovers: 99th (3 fumble recoveries)
3rd down D: 34th