You have to understand Boston fans are some of the most cuckoo fans in the world. They think they're steps away from the championship. They think Al Jefferson is the next Dwight Howard and Tony Allen is just as fast as Parker. They think Pierce is awesome and with the right coach, instead of Doc, they'd be at least EC champs.
Seriously now, their FO knows that if they get Nazr Mohammed and scrubs for their franchise guy, it's pitchforks and torches. You don't tear up a championship squad like that.