It's an interesting thesis and topic of conversation and it's nice to see some actual football talk if only to distract from all this coaching craziness going on. There are positives and negatives to each philosophy, but I will say I'm a 3-4 guy based upon my own experiences.
At its base, the 3-4's got 3 defensive linemen, which consist of 2 DE's and 1 DT/NT. All three of those linemen have two gaps to fill and it's their job to stop the run. Your LE is responsible for the gaps between the TE and RT, and RT and RG. Your DT/NT covers the gaps between RG and C and C and LG. Your RE watches the gap between LG and LT and also covers the weak-side. Your Mike LB's are primarily there to back up their DL in run support, which is essential because there are 5 guys on the offensive line vs. 3 on the defensive, so your mikes have gotta be on the ball and able to shed their blockers and stop the run once it gets beyond the line.
One thing the 3-4 requires is an absolute stud at NT, and here I'm talking about someone along the lines of a Jay Ratliff. He needs to be durable, have stamina, speed and size, because in the 3-4 he's either going to be double or triple teamed while also needing to watch his gaps for the run. It's a lot to ask and a lot required from the NT position, and that's why you need a true stud- and whether Jewhan Edwards could be that guy, I honestly have no idea. It's an intriguing thought though at the very least. One qualifier though is that finding a true stud at NT is much easier said than done, because it's possibly the most difficult position to play in a base 3-4.
Another key is the OLB's, who are the main pass rushing threat in the 3-4, but it's also essential that they have the speed, awareness and ability to drop back in coverage and do that successfully. They need to do both, and the best of them are able to do that, but the most critical thing for your OLB's is that they need to generate a strong and consistent pass rush, because without that the defense will collapse under the absence of a pass rush, unless you revert to an all or nothing strategy of running straight-up blitzes in order to try and pressure the QB, and that's playing with fire and you *will* get burned.
A 3-4 defense generally requires bigger LB's, as those LB's will have to deal with offensive linemen who are much, much larger than them. A 4-3 in theory has the advantage of creating pressure from your DL and thus freeing up your LB's for other duties beyond pass rushing (unless you've got a true freak like a Ratliff who's able able to generate massive QB pressure from the NT position in a base 3-4), while the 3-4 carries the advantage that the opposing OL isn't quite sure whom to block, as the pass rush can come from any area.
There's much more movement involved in the 3-4, more players behind the line of scrimmage which makes it that much more difficult for an offense to read. But you really need the right personnel to run it correctly (and that is essential), else you'll have to revert to blitzing in order to generate sufficient QB pressure, and that makes it very vulnerable to just a pounding run game straight up the gaps or middle, and especially vulnerable to the play-action pass ya know, one of those 8 yard flare-outs that turns into an 80 yard touchdown.
Anyway I'm babbling on, but great topic and nice article Doogie!
