OK, you're making arguments that these teams need to save money but hardly anything about the trades themselves. There is more than one way to skin a cat.
I understand there are other deals they could do... but they need a team under the cap to do something meaningful. Those teams are Houston, Detroit, San Antonio, Indiana, Orlando, and OKC... Vic and GP2 might fit in some trade exceptions so maybe the market is wider for those guys. In any case.. the market is limited to like 20% of the league. Houston has some goals with their cap space so may not take on a salary dump. OKC may not want an obligation that long... so you are down to a few teams.
So there are other suitors... but the pickings are slim.
I don't doubt that ATL wants to get rid of salary, just doesn't seem like an ideal trade for them. This goes for all draft day deals, but it has to be really really good because it eliminates any kind of alternative they might in the summer. I don't look at this deal as one that's so good they have to do it and forgo all their other options. With a new coach and FO, they might not even want to go with a different direction. They don't need Kelly, and I think the guy they should really think about trading is Capela. They already have the younger player who needs to be extended and might already be better than him. Capela also likely has more value and they might even be able to get something for him on his current deal. If there is a Collins salary dump in the future, I would expect it to be during FA and executed with the 2024 pick they own from Sacramento.
I think KO gives them something they need as a stretch big. Could literally step into the lineup in JC place for a year. Capela's trade value ain't gonna be higher than Collins. Limited center that has stuggled at times to stay on the court. They also kind of need him as a lob threat for Trae and Quin without a drop center? Say they did find someone to take Capela... they need to send back $10M less (or more) in salary and get a solid player in return... without adding draft comp... they also need the contract they acquire to be expiring.
You may be right on the timing... but I doubt that is ideal. A few teams will drop out of the cap space game while you wait and your options get more limited. A couple may end up realizing their space isn't going to be worth what they thought and may end up settling for less. If they have to add the pick later then I'm guessing they would have rather just done a swap and moved back. It also lowers the cap hold on the pick they make... when you are strapped as Atlanta every million helps.
Not trying to be antagonistic or have a big dialogue here... just giving more context as you mentioned I didn't talk about the quality of the trade.
I also don't doubt that GSW wants to shed some money, but I don't think they will have a problem finding a suitor for GP2. It should take a couple seconds max, and they have that. Tbh I would take GP2 on his contract right now for free. He's a good player. They also might not not need to dump him if they plan on moving Poole, which feels likely. Again, this just doesn't seem like a knockout deal where they should forgo any future options to get it done. They could go a different direction with how they want to cut salary and even if GP2 is the guy they decide they need to shed they still have the means to dump him later in the offseason.
They don't have a ton of options to cut salary unless its with meaningful players (looney, Wiggins, Green) or a guy like Poole who is at his lowest value right now. It will be more expensive than a pick swap if they have to do it in season. A pick swap from 28 to 19 is essentially worth a few seconds... ish.
GP is a hard one to gauge... I think since he has really only been effective in GS teams might think they are getting something less. He's a good player... with some injury issues (is the core thing lingering)... and is paid in a range that isn't wonderful. Flipping GP for a minimum is their path of least resistance to saving money. Maybe they find a cheaper way to do it but I'm telling yall... teams gonna get tight this summer. These types of deals may not feel the brunt of it but dumping salary will not be as cheap as it has been in the past. No one wants to help GS either.