Even before Tom Thibodeau actually left the Celtics to become the head coach of the Bulls, Doc Rivers was considering Lawrence Frank as the replacement to be in charge of the team's defense.

“If Lawrence had fallen through, then that would have been more difficult,’’ Rivers said. “Because you really want someone to do that, instead of you being the head coach having to do it, because then that takes away from your ability to coach the team.’’

Frank comes from the Pat Riley coaching tree.

“You [couldn’t] bring to those players someone who is learning on the job,’’ former NBA coach and current TV analyst Jeff Van Gundy said. “They needed to replace Tom with somebody who was well established in an NBA circle, who the players could instantaneously know was really good at his job, and they found that in Lawrence.

“They didn’t try to change things. They had a formula that was sound and simple and effective, they stuck with it. But it’s definitely consistent as much as how it’s taught. Tom is a superior teacher, and they replaced him with a superior teacher as well in Lawrence.’’

“Our defense is Doc’s defense,’’ team president Danny Ainge said. “It’s not Tom Thibodeau’s defense. It’s not Lawrence Frank’s defense. It’s Doc Rivers’s defense.’’