Sadly, we're in a vicious circle with recruiting.
We get negatively recruited against on linemen by coaches who say we won't put them in positions to make plays.
Therefore we end up with guys who may be good 3-4 2-gap fits but not quite the athlete who could make a terrorizing impact at the position.
The DL ends up not making much in the way of sacks and TFLs thus giving credence to the negative recruiting.
There is plenty of playmaking to be made at end in the 3-4 and the greats get paid well. Justin Smith is an absolute terror as a 3-4 DE for the Niners, much the same for Haloti Ngata on the Ravens. If we could get some of these guys we have near misses on, I think the DL production would go up.