I think I read on CB just in the last couple days that the Celtics talent evaluators, as a whole, believe that the BKN pick will end up somewhere in the 5-9 range, which is one of the main reasons Danny was okay with trading the pick. If it indeed ends up in that range, the odds of landing a cornerstone go way down. So, I think Danny's final thinking regarding the IT-Kyrie trade can be summarized in the following equation:
Lower BKN pick + IT's hip + IT's age + IT's Brinks talk = better get Kyrie while the getting's good
I think this is pretty much spot on. It was a combination of things, not just one thing:
1) A significant uptick in tanking teams, especially in the East, made the Brooklyn pick much less of a sure thing.
2) IT's injury, age, contract status, and defensive mismatch capabilities made him a prime candidate to be moved at this time.
3) Kyrie being similarly skilled at this point, while also being younger and potentially still having a higher ceiling to reach, made this gamble worth it to Ainge allowing us to compete both now and in the future.
Would we have made this type of trade if IT was healthy? Doubtful. Would we have necessarily trade IT in a similar situation if Kyrie wasn't available? Unlikely. I think this was just a perfect storm of occurrences that led to this trade and Danny finally giving up that pick.
But let's get one thing straight: due to IT's injury, age, and size, it is very, very unlikely that he would've ever led us to a title as the best or second best player on our team.
While it's no certainty that Kyrie will lead us to a title, his age/timeline, yet-to-be-reached ceiling, and better overall size gives him a much higher likelihood of leading us to a title than IT. I don't think this is arguable at all.
So when considering that fact and the context of IT's injury, contract status, and the much greater uncertainty of the Brooklyn pick, I think Ainge was clearly justified in making this gamble of trading the Brooklyn pick.