As arguably the greatest coach in basketball history, Phil Jackson won 11 championships with Michael Jordan, Scottie Pippen, Shaquille O’Neal and Kobe Bryant.

If anybody would know the differences between those all-time greats, it’s him. In a panel at the MIT Sloan Sports Analytics Conference, Jackson shed some light on their work ethics.

“Shaq didn’t work at it,” Jackson said. “Michael was able to succeed despite all kinds of limitations in his game. He couldn’t hit an outside shot. He couldn’t defend. But all of that went away because of his work ethic. Kobe saw that as a pinnacle that he had to reach, and he took it to a whole new level.”

After winning three straight titles with the Los Angeles Lakers from 2000 to 2002, O’Neal and Bryant had a famous falling out, and Jackson pointed to their personalities as a cause.

“Shaq had a clown role he had to play,” he said. “So that was part of the rift.”