I have to say that I lean towards Wolverine on this one....
I firmly believe we have more talent on D than what our results show.
I don't think Zimmer is a bad coach or d coordinator, I think he's done a pretty good job. At the same time, I think there are a few D coordinators out there that would really make our Defense ferocious and increase our sacks and takeaways significantly.
I know that we're young and that we could use another LB and a FS but even the Raven's championship defense had one or two guys that weren't probowlers.
The biggest problem i have with Zim is that he hasn't been able to take a talented college DE and coach him into a passrushing terror...and Lord knows we've spent many first rounders on finding one. The last one we had was via FA.
Overall, I think Zim is a great bend but don't break guy but just flat out horrible at finding ways to get pressure on the QB and poor at coaching passrushers individually.