Norm did not blitz. We blitz way more under Phil than we did under Norm (albeit, still not much) and substitute way more. Norm's whole thing was staying in base and preventing the big play. We just had crazy ass DLs and the occasional Bob Sanders, so it felt like we had 10 guys in the box.
Honestly I don't remember well enough to say for sure but when Norm was at Vanderbilt he blitzed all the time. It's conceivable early in his career here at Iowa when we had less overall defensive talent and athletes we blitzed a bit more to manufacture some pressure. But as the athletes caught up to our scheme we definitely didn't blitz much.
But two things you said that I think have been great improvements for us. Number one that 2010 team really fell off the edge. I personally think because we didn't have enough of a D line rotation.. and we were gassed. Coupled with the fact that I think we played 14 different linebackers because of injuries & the DL trying to do much. I really do believe that was a recipe for our difficulties down the stretch.
We have made a concerted effort in recent years to grow that depth and play more guys. Coming from this very uneducated eye it looks like we have better high-quality depth down there than we have ever had. We also play a lot of Dbs in the backfield so from a defensive standpoint. What has always been a very sound to great D, that could be gutted by injuries. I believe has become one of the 20 or so most gifted and athletic in the nation, 2 deep in most cases.
Per the blitzing...yes Phil blitzes a little bit more. But probably more important than that. They clearly spend some time practicing it because when we were doing it years back, not only did we not do it much but we were not very good at it. I'm not a huge blitz fan anyway. But when we do it and we don't get home and we leave a guy on an island I really don't like it.