Greene is in the discussion for greatest defensive tackle in history. But what made him the greatest Steeler was his selfless commitment to winning. He was a superstar but not a diva.
This is from an old post:
The clincher, to my mind, is that Greene was the acknowledged leader on that team. As Rocky Blier puts it: "If Joe didn't like something, none of us liked it. If Joe says we should do this, we all did it." It was Greene who kept the Bradshaw/Gilliam controversy from becoming a black-white issue in the locker room. Greene's ferocious desire to win helped Chuck Noll change the culture of losing that surrounded the franchise. Joe's influence kept the team together when the WFL started raiding players.
The selection of Joe Greene in 1969 changed the fortunes of the franchise. Other great players followed, but Joe was first then, and he is first-among-almost-equals today.