First off, I'm floored that they traded away their so-called defensive anchor and second-best defensive center in the league.

However

(1) They got a piece for the future - Jeff Green's athleticism and game will be good in the future when Rondo is the cornerstone.
(2) If there is a lockout and the older veterans retire, you have a rebuilding piece already in place
(3) Jeff Green matches up very well with LeBron James size-wise and athleticism-wise
(4) The Heat have no size, either - Garnett still beats Bosh on experience and testicles while Glend Davis is better than any of their bench bigs
(5) Dwight Howard can't carry the Magic - he just doesn't seem to have it in him to dominate.  I've seen games where he's scored high and I think they lose a good portion of them.  I've also noticed that when his scoring goes up, his rebounding drops a little to 10-12 rebounds versus his usual 15.  We still have Shaq to match up against Howard (and we could possibly bring back 'Sheed)

So there.  I'm not happy with the trade when the Celtics were already #1 in the East winning at a 74% clip, but maybe they see a lockout where the Big Three retire.  I know members of this forum pointed out that Ray Allen's shot got flat a week ago signifying that he was wearing out...