Celtics assistant Mike Longabardi, who was Doc Rivers' "defensive coordinator" in Boston, has accepted an offer to become an assistant for Phoenix Suns head coach Jeff Hornacek, a league source told the Globe.
Longabardi becomes the first assistant coach to leave the Celtics this offseason, which has been filled with questions about whether Rivers will return to coach the team.
Longabardi was the Celtics defensive coordinator. He had been with the team since the championship year, but received a promotion when he took over for Lawrence Frank. With Doc's situation up in the air, the Celtics assistants have no other choice, but to explore other options. The Suns new GM Ryan McDonough is obviously familiar with Longabardi after working next to Danny Ainge the past few years.