Raji a penetrating pass rusher???? Never has been, never will be. He's been a run stuffer all the way, and it was often noted during broadcasts last year that the run defense was a weakness BECAUSE he wasn't there.
In addition, I think you are way off on Capers philosophy. What I think he wants is more pressure from the front 3 (or 4, depending on formation) so that they don't have to blitz to get some heat on the QB. And teams can and do run to championships (see Seahawks, Seattle) but those teams tend to fold when you take that away from them.
In the NFC this year, the toughest opponents we'll face (Dallas, Seattle, Minnesota, Arizona and Carolina ALL try to establish the ground game and run play action off it. The return of Raji to the middle should certainly help with that, assuming he has anything left.
"The difference between genius and stupidity is that genius has its limits" --Albert Einstein