A base 3-4 pretty much always rushes 4 players. They can just diguise who's rushing much better. You run a 3-4 when you're DC is learned in that craft, then you recruit to fill the 3-4. Burnham has never run a 3-4. We've had a couple of game schemes where we used 3 down lineman before, but it was not a 3-4.If we can't get pressure with 4, taking a guy away won't help. If we want to blitz linebackers, just do it from a 4-3. Btw, you run a 3-4 when you have one huge stud nose tackle. Thus allowing you to play a man short on the d line