Why would the Atlanta Hawks trade for Carmelo Anthony to immediately put him on waivers? Is it just to clear cap space?
From my understanding, the Hawks are trying to set up some moves for the future. Part of that is hoarding some draft picks (they received one in this deal), part of it is keeping cap space available (why they waive Carmelo--but they also get rid of Schroder's salary), and part of it is developing good, younger players (they've opted for PG's other than Schroeder--so they wanted to get rid of him but needed a trade to do so).
From OKC's perspective, they didn't want to keep Anthony's contract but instead of waiving him themselves, they looked around for such a deal where they could land a player or two that they want but for whom they'd need to trade (and not wanting to trade away much else but Anthony). Yes, the Hawks waived Anthony to keep cap space but you could look at it as them doing the waiving for the Thunder with a middle step in between that benefits both teams.