Given the ex-Celtics fetish, what about Ed Pinckney?
He's interviewed twice with the Grizzlies, although some think he is being considered for a lead assistant coach role rather than the top job.
He's been an assistant under Tom Thibodeaux for the past three seasons, so he can continue the same style of defense. He was initially hired to coach big men, which might help with Fab Melo and if the Celtics draft a big. He has a reputation for "good rapport with players", whatever that means. As a player who twice was in the top ten in offensive rebounding percentage, perhaps he will be a godsend to people who hated Doc's rebounding principles.
And it is perhaps delicious if Ainge hires a guy he was once traded for.
For those who want a cheap, inexperienced coach who can grow with the team, Pinckney sounds like an option.