A team needs many elements to make a 3-4 defense work effectively. It needs a stout nose tackle to gobble up blocks and protect the interior against the run game. It needs speed off the edges from the outside linebacker to get pressure on the quarterback. The Patriots have the massive nose tackle in Vince Wilfork, but they lack the star power at outside linebacker.
The Patriots dipped into the free-agent market before the 2007 season and offered a big-money deal to former Ravens outside linebacker Adalius Thomas. The move never paid dividends, and he is no longer on their roster. That deal prevented the Patriots from going back to the market and it has left them a little weak at the starting and backup spots.
They are pretty solid on the right side with Tully Banta-Cain. However, he is coming off a career season and it will be tough for him to duplicate the 9.5 sacks he came up with in 2009. While he is a good overall athlete, he did not get many of his sacks based on athletic ability alone. Some of them were a result of the design and schemes used by head coach Bill Belichick. Banta-Cain can also be a little bit of a liability at the point of attack in the run game where he struggles or often runs himself around blocks and gets out of position.
The other projected starter is Rob Ninkovich. He had limited playing time in 2009 and recorded only one sack. Ninkovich is a tough, blue-collar guy but he is not the athletic, explosive outside linebacker the Patriots need. I think they see him a little like a younger version of former linebacker Mike Vrabel, but he is a long way from being that right now.
While they have a lot of bodies at the position, they do not have great depth. The overall effectiveness of this group could fall on rookie, second-round pick Jermaine Cunningham. Cunningham has the physical tools to contribute early but will he be able to pick up one of the more complex defenses in the NFL?
Belichick is a master at coming up with schemes to cover up defensive deficiencies and he'll have to do that for their outside linebacker position this season.