It is tough to sack the QB. With the settings I use I have about 1 to 2 seconds in the pocket. And the computer gets 5 to 7 and then still throws the ball away at the last moment before the sack.
But I have found a way to get the sacks, by dropping 10 into coverage and usering the OLB or DE. Just give the QB a few seconds, while you hang back with the linebacker/end, looking for bubble screens and HB dumps. Then start moving in to the QB, to draw the o linemen away from your one rushing nose tackle. I hardly ever move all the way in on the rush, just a few jukes around one side then maybe a juke around the other side. Just enough to draw some blockers.
I once got 7 sacks with J Ratliff in one game. Coverage sacks are the way to go to bump up the defense stats. I use Nickel, 335, cover 3 inside blitz, then just drop the linebackers into coverage. Easy to set, F@G D.