I don't think there can possibly be any doubt that we need a healthy Rosey Colvin to become a dominating defense.
He is one very important piece of the puzzle - OLB supreme! Hopefully they can rework his contract to everyones satisfaction. He seems pretty happy to be here based on what I have seen. He knows the system and has flourished in it.
Show me a healty Colvin / Thomas / Vrabel / player X & Y (some new bodies), along with another year from Seau & Bruschi and then something from young players (Woods, Alexander, Lua) and finally a new rookie or two and I will feel pretty good about our LB corp.