Unless he's really fallen off and I haven't noticed, Jerod Mayo. And what Belichick's done is take a chance on young, very talented players and it's paid off. Hernandez and Tate just needed a shot and the system fits their talents well. It really has been a good job by Belichick, though they've also gotten some luck this year. i realize i might put too much stock into them for teams/players i haven't seen a lot of, but PFF rated Mayo as the worst ILB of the past week, and has characterized him as having a very up-and-down season: