Barnett's a good enough LB that even non-Packer fans have taken notice. He is not elite, but he covers a lot of ground and brings some enthusiasm to our defense.
I remember when people would criticize Junior Seau for overpursuing plays. I always thought that was silly. Overpursuit is the downside of being fast and reacting quickly, but it does not come anywhere close to cancelling out the good plays that are made because of speed. Maybe we should find us another slow MLB, like Bernardo Harris. He never overpursued. But he didn't make any plays on the edge, either.
Also, somebody said that Barnett gets gobbled up by guards and centers. How many linebackers can take on an O-lineman and win? Not many. It is the job of the DT's to take on the guards and centers.