I think the C's could have gone either way. Here's the reason why. Even with Jimmy Butler, they aren't beating the Cavs or coming close to the Finals this next year. Also, NEXT year they have the Nets 1st round pick. The Nets got even worse for next year which means the Celtics will have that 1st - 3rd overall pick again, and they can package a deal for a star the following year.
Also, in order to get Jimmy Butler it would have had to been more than a 1st rounder AND Avery Bradley. Chicago wasn't going to take that cause they could get more for him. And if we lose Bradley we're losing a vital defensive player as well.
I don't know. I think this was a good move for the C's considering they aren't contending this next year either.