I was on the site two days looking at designing a S&T scenario of KD to the C's. Wasn't sure as to if KD's out going number (if he had a 20% pay raise and going to a team over the cap) was still only counting as his last year's cap number? I do understand a third team would be needed to absorb cap part.
I believe the bigger problem is Boston being over the apron at the time of the deal. It's not the money involved. And Boston would not be affected by BYC problems or any of that, that's GSW's problem, if that actually applies here. If it does, it's just another reason why GSW wouldn't do a sign and trade of Durant.
I definitely know there are four teams that would be suitable third parties and C's have all those first round picks to entice a team to assit. I do think BYC would apply in this case and C's can get under the apron but I don't see either as a big hurtle if the right third team comes in. Biggest issue is I really don't feel KD would leave GS for Boston though. Warriors are the best shot and continued winning. NYK is a maybe as he may feel he can grow his brand there.
If BYC applies, and if Durant gets a max contract it appears it does apply, then it would be up to GSW to figure out how to make it work since their outgoing salary wouldn't be matching their incoming and only they know how they would want to handle it.
There would most likely have to be teams involved willing to send GSW salary to make up the difference. Those teams would need to be under the cap and there most likely would need to be a bunch of picks moving between the teams involved.
It's all really complicated and complex and I really see no reason for GSW to do it.
Then you have the Celtics apron problem. They are over it currently and would need to do a bunch of stuff to be under it after the trade and then would be hardcapped.
Don't see Ainge wanting to be hardcapped and give up other players or right to re-sign players to make the deal work.
So Boston doesn't look like they would do the trade and I don't see a very intelligent Warriors front office jumping through hoops to get the best or 2nd best player in the league to a team that could be perfectly positioned to end the Warriors title run after they get Durant.
The whole "get Durant to Boston" is pretty much a Boston fan's dream but it really has no chance of ever happening in real life.
You can go ahead and do all the research and actually create a scenario in which this trade is possible. But it will be all for nothing because how you run a business has to come into effect and neither Ainge nor the GSW front office would do this.