I'm happy the deal got done, but I think the Celtics got their bluff called. Not only is the cap going down a good amount this year, and will likely go down the year after that too, but Rondo is still missing some glaring parts to his game.
Think of it this way: Rondo has not made much money so far and is one injury away from not getting that type of contract that will make him "set". He should have felt the pressure more than Celtics.
I love Rondo's game, but just wait until the Celtics play a real playoff series (i.e. Orlando, Lakers, Spurs, etc). Rondo dominated the last two regular seasons but was often times mitigated in the playoffs due to his lack of a shot. It WILL happen again.
Again, I'm happy about the signing so that everyone can entirely focus on banner 18.