Edit: also, for anyone confused by the whole discussion, BYC is Base Year Compensation, which makes sign-and-trades very tricky when a player gets a raise of more than 20%. It also applies to Rozier S&T ideas, as he counts for different salary going out than he does coming in. It's addressed in question 93 of the FAQs
I remember having no idea what BYC was so this is helpful information.
It has been mentioned a number of times that a team trading a s&t player only counts for half of the money going out for the outgoing team, but for the full amount coming in for the receiving team. I think people generally have a handle on this idea - especially as it pertains to a Rozier s&t to the Pels.
However, there is another piece of BYC that many people seem to have overlooked (including myself recently) and this one has to do with Kyrie. For example, say Kyrie decided he wanted to sign with the Knicks, but didn't want to leave us with nothing. He could agree to a s&t with them, but since the Knicks are well below the cap, we could receive a nice TPE. Let's assume this is enough for Ainge as incoming players would just lower that TPE.
Now, everybody may assume that we would be receiving a TPE in the amount of the first year of Kyrie's contract, but that is not the case. Because of BYC rules, we would actually only be receiving a TPE in the amount of $20.1M - the amount Kyrie is making this season. This was put in place to prevent teams from circumventing the cap...(which makes no sense to me; if the league was going to allow a team to sign a player to that new contract, but the player wants to leave, they are essentially letting that team get screwed over).
Anyway, that $20.1M TPE is certainly nice, but it would not be enough to take in a player like Conley. We would have to lower our expectations on what type of player we could trade for using picks as compensation.