I give you the 2009-2010 Detroit Pistons.
This is what happens when
(1) you hang on to aging stars for too long (Hamilton, Prince)
(2) Let key players go for nothing instead of trading them first (Rasheed Wallace, Antonio McDyess)
(3) trade away your key playmaker for an aging player with a big expiring contract (Billups for Iverson),
(4) and then use the resulting cap space to make dumb free agent signings simply because you can.
After winning a title a few short years ago, the Pistons are no longer relevant. Hopefully Ainge has learned from Dumars' mistakes, but you never know.
If we could get to 6 straight conference finals - that would have been a spectacular run. Really, this was a Faustian bargain, we knew it in 2007. But it won a title, and it made the Celtics relevant again - and it probably helps them be a target for good players again.
Really the key is 2012, when KG's deal runs out. Have to be careful about letting deals go past that. Rondo's was a sensible obvious exception, and if they re-up Perk, he will also be a fair exception. Basically how the Spurs roll, where all their deals are tied in length to Duncan's.
In the meantime, they have Allen's expiring to move - but only if they can get a legitimate part for it. Otherwise, better of filling in the edges and working with Ray. His quickness is not there anymore, but his virtue (shooting) is something that generally ages very well compared to other basketball skills. You know how it goes, be tall, be a good shooter, be a good passer, there is a chance there will always be some work out there.