I think you underrate how well Kearse DOES defend the run... yes he's obviously a monster pass rusher, and he's a bit light, so when you run right at him he can be taken advantage of, but I've lost track of how many times I've seen him tackle a RB from behind coming from the non-play side, to break up a play, so he does help their run defense... I think you can attribute some of Barber's increased run efficiency late in last weeks game to fatigue, and some to D playing to stop the pass, but some of it, I believe, comes from losing Kearse... If you think about it another way, his ability to cause QB pressure isn't replaceable by 1 player, so to get that back you either have to involve more resources to pressureing the QB (which will take resources away from stopping running plays) or you put less pressure on the QB, which could weaken the overall D.