His 19-year career is one of the greatest ever, but a couple more years would have made it even more historic.
The center helped the Celtics win NBA titles in 1981, 1984 and 1986.
Just 10 players in basketball history have managed to win titles with two teams while also making it to the Hall of Fame as an individual.
Three players who have won championships with the Zen Master say New York must show patience.
These three NBA champions understand the safety issue but say the league has gone too far with calling flagrant fouls.
Asked if his former teammate made him a better player, the seven-time NBA champ says plenty without actually answering the question.
In the spirit of Black Friday steals, here are transactions in which one side got way more value than the other.
Greatest NBA Trios