There's been some suggestions that switch to a 3-4 would be good. I think there are some big problems with that, but I'm an armchair football player, so I thought I'd put it in a FanPost for discussion. Obviously the biggest problem is the personnel. As I see it, the biggest need for a successful 3-4 is what Gregg Easterbrook calls a Ticonderoga-class Nose Tackle. Guys like Ted Washington, who eat up two offensive lineman on every play. There are so few guys like that in the league, I think that's one of the reasons not a lot of teams play it.
I'm not sure what I would call this scale (size or quickness) but I would order these positions like this: 3-4 OLB, 4-3 DE, 3-4 DE, 4-3 DT. The positions just don't line up. Kiwi is probably the one guy who could be a 3-4 OLB, and maybe Tuck could be a 3-4 DE, based on his play inside last year. A DE in a 3-4 plays more like a tackle and eats up lineman so the LBs can make the plays. The biggest reasons the giants have gone away from the 3-4 in the last decade is because MIchael Strahan was at least one of the three best 4-3 Defensive Ends of All-Time.
At LB, we can barely field 3 LB's right now, so I don't see how we could field 4. I think I saw an interview with Accorsi (maybe), where he said one of the biggest reasons for not implementing the 3-4 is the cap. LB's cost more then lineman. That's why the Steelers have to turnover their LBs so frequently. With the money we're going to tie up in Eli and Jacobs, I can't imagine being able to afford a 3-4 for more then a couple of years.