It's been said before, but this is one of the concerns about having a defensive minded head coach. Of course, there are exceptions, but the constant revolving door(Weis! No Pease! No Roper) isn't healthy for most head coaches. If you got to volnation, these poor schmucks are almost in as much panic mode as they were at this point last year looking for a head coach. And the funny part is, even if they'd landed him, how long do they really expect a former HC to be their OC? They'd be back in the hunt in less than 2 years, meaning that anyone that signed to play for him and his style would be left with whoever they get next.
Defense wins championships, but you have to offense. And you need to have continuity. With as many different schemes and mindsets as there are today, I think the offensive side of the ball is much more coordinator-sensitive. Guys like Itraz and others are much better at explaining the particular nuances of each scheme, but you can take a less than perfect fit at LB or DB and make it work. But having a pro-style QB and OL in more of an RPO scheme is a disaster--and the same if you have an athletic QB and OL forced into a traditional. So this up and down situation with their offense, and constant identity change, is going to cause problems for them in recruiting and player development just like it did with us.
If you reverse things, not one single person would be worried if Grantham, or the next DC went elsewhere.
I'm not the biggest fan of everything Mullen does, but I do like the fact that we have an identity based around his offensive mindset that will eventually be manned with all the right people. The situation in Knoxville shows just how bad the alternative often is.