Miami gets expiring contracts and a good player that can help them compete now. Either keep him, sign and trade him in the offseason for other players, or let him walk with no risk. Getting a first back for Jimmy at this point while the team and front office all publicly want him gone is unrealistic. But this is a good return for a team that isn't looking to rebuild and is playing damn good basketball right now.
Philly gets Jimmy, the guy they've wanted the whole time anyway and get out from a long term contract that they just gave to Paul George.
Suns get Paul George, who's a significantly better fit for their team compared to Beal. Taking on longer money, but no no-trade clause, more defense, better fit, and SLIGHTLY cheaper.
Pels get three firsts for taking Beal, they get $15M in immediate cap space, and what might be sneaky true: Beal may find a resurgence since he'll be able to play his actual position again there. He's the outside, 3-level scorer. In phoenix, he was triple-redundant. In NO, he is who the pels have been trying to make Brandon Ingram into while also ending up collecting three firsts for a player that just works.
Pistons get CJ as an upgrade at SG plus 3 seconds for their time. He costs twice as much, but it's not long-term money, he's a great vet for young guys, and he'll help Detroit play some meaningful games in the playoffs. That expiring contract next year will be valuable as well.