One thing to consider is that the Pats rarely allow the ends to just go all in on rushing the QB. They often play with more contain responsibility than other ends. Both towards the QB, but also towards the RB in pass routes in the backfield. Chandler had 11.5 Sacks in 2013, that's pretty good for a 4-3 end. It tied him for 7 in the league in sacks. Sure, it's not JJ Watt good. But as I've said many times here. There is a huge gap between being an average end, and being JJ Watt. And Chandler Jones is above average.
I also think that people severely underrate Chandler as a run stopper. He was aweful in the Chiefs game at it, but hey, all players pretty much sucked that game. And since then people has started saying how bad he is at run stopping. He is not perfect at it. But he is pretty good.