I am not sure if you could call him a rookie but James Harrison was a fucking beast in his first full year in the league and first year playing for the Steelers.There hasn't been a rookie that played great on the Steelers' defense since Mean Joe. Even Troy was pedestrian in his first year.
Before 07 I don't think he ever got any playing time other than some special teams.
Of course by then he was like 6 years out of college.