Holmgren won a Superbowl before he became a re-tread.
Dungy and Schottenhiemer had teams playing in conference championship games.
A re-tread is a guy who has coached for a while and done nothing. Not one who has had some decent success. Belichik was a re-tread after his stint in Cleveland. He has been the exception to the rule that a re-tread will actually show improvement.