I'll preface this with I was disappointed the Celtics gave up the Brooklyn pick, and I'm actually not a big Kyrie fan.
But with that said, I think this is a win-win for both. The Celtics had an IT issue they were going to have to deal with sooner, rather than later. I heard a stat on Mike and Mike this morning that no player in NBA history over 30 that is below 6'0" has ever made an All-Star Team. Couple that with IT's hip injuries, and I think this is a clear indication that the Celtics did not want to give a 29 year old, extremely undersized point guard a max contract next summer.
Kyrie fits the Celtics timeline much better and has a much better contract situation. Crowder has a great contract which is tough to lose, but he was going to lose playing time with Hayward, Brown and Tatum in the fold. As far as the Brooklyn pick, it sucks to lose it, but there's a chance the Lakers pick (2-5) the Celtics have could actually be the better pick. The Nets added Russell, Crabbe and Demare Carroll this offseason and playing in the East (which is even worse than last year) they could be more better than the Lakers. So, the Celtics got a 25 year old perennial all-star who has a championship and a Gold Medal, yet still maintain flexibility with picks and their young players. So, we gave up more than others have for stars, but didn't leverage the future.
Cleveland should be really happy. They're set up for another championship run this year, though I think they'll find out IT is great, but teams really figure how to exploit him in the playoffs, and they' got assets should LeBron bolt.
Don't love Irving, but the deal itself is a win-win.