We don't play a 3-4.
We play a base 3-4, two-gap system, but the mix is substantial enough that some games you hardly would know the Pats "are a 3-4 team."
This is why the Pats emphasize versatility as a prime team and individual value. They already play 4-3 sets, it's just not the base defense. They also play a variety of bizarre variations that suit the occasion. The only real constant is that the guys on the line are responsible for two gaps, not one, with additional linemen adding either a "wildcard" for the offense to cope with, or additional emphasis on those gaps. You can also drop a guy back into coverage (oh my he was the OLB all along!), blitz him, whatever.
Yeah, I'm pretty fond of the 3-4 as the Pats play it. This is why they can look like Blitzburgh one week, like a textbook, patient, grind-it-out 3-4 team the next, and like a ballhawking risktaking defense on another week (or on another down in the same week - whatever.) We lost a lot of that last year, due in large part to injury. But the versatility of the Pats' defense is what's distinguished it for all these years. They'll never be like Chicago in 85-86, or Baltimore in 2000-2001, dominating every game, smothering and frustrating every opposing team (and doing it the same way on pretty much every down.)
They'll just beat you, and leave you wondering how it happened this time.
PFnV