Allen is an old player and he wants to win something before retiring, so he went to Miami to be the sixth man.
I'm a Celtics fan, I really love Allen and I can't blame him.
The only thing that Boston could do right now is to build a new, and young, team from fundamentals around Rondo.
Yes, Heat are stronger with Allen, but NBA is unpredictable....just remember Mavs vs Heat two years ago.