Martinez is an above average LB? Based on what exactly? His tackle stats? He led the league in tackles because the Packers had one of the worst defenses in the league, and they can't get off the field, therefore more opportunities for tackles.
Is he a difference maker? I certainly don't think so at this point. He had only one INT last year, and one measly sack. Tackles are nice, but they aren't the sole measure of a great LB. I'd argue that he looks much better than he is merely because the rest of the defense is so awful. I remember AJ Hawk piling up a ton of tackles too, in fact he is the all time leader in tackles for the Green Bay Packers. Yet, nobody considered him a great LB, and for good reason.