Boston Celtics general manager Danny Ainge thought Doc Rivers was going to be the next Gregg Popovich, Jerry Sloan or even Red Auerbach - coaches who stayed with one team for decades.

Rivers got the nine-year itch.

”He felt like it was time for a change. He felt like we all needed a change,” Ainge said on Tuesday night after the deal to allow Rivers out of his contract to coach the Los Angeles Clippers was final. ”That was his rationalization, or justification, for going to the Clippers: that this was better for everybody.”

After weeks of negotiations that at one time had Boston stars Kevin Garnett and Paul Pierce joining Rivers in Los Angeles, the Celtics announced on Tuesday that the NBA approved the deal to allow their coach to go to the Clippers in exchange for a first-round pick in 2015. Ainge said in a news conference that he had not begun looking for a new coach because he couldn’t believe until late in the on-again, off-again process that Rivers was actually leaving.

Reported by Jimmy Golen of the Associated Press