We're not talking 4-3 here, specifically, we're talking 4-2-5 or 4-1-6. Subpackages. The Pats spent 57% of their snaps in them. The problem is that the offense can still run the ball when the defense is in subpackages. You can't stick a situational pass-rusher in every time the defense in in a subpackages because that's when they run right at him and get 12 yards on that 2nd and 10 that you sent in the nickel for.
Green was probably a bad example, but I never even said I wanted him specifically. I said a "Jarvis Green type." Less specifically, that's a big DE who can hold his own against the run (in a 4-man line, to whoever mentioned that Green was a liability against the run, which he was in the 3-man line), but still get some pressure (14 sacks combined in 06 and 07). I could have easily said that I prefered a Julius Peppers, Mario Williams, Willie McGinest, Jared Allen, or Justin Tuck type player, but that doesn't get the point across. The Pats don't need an elite pass-rusher like that, they need somebody who get get more than 5 sacks a season (Green's 06 and 07 sack numbers would have led the 2010 Pats) while not being a complete liability to the already questionable subpackage run defense (i.e. Matthews, Miller).