Fox has started the year kinda rough (especially his shooting), and I'm thinking the Kings may be regretting giving him that max contract, especially with two younger point guards on the team (Haliburton and Mitchell).
This would let them get off that contract, give those two young point guards a bigger role, and make their roster more of a threat to make the playoffs, which their owner is eager for. Plus they'd also be getting three first rounders (note on that, this site is wrong, and that one 2023 Nets pick is actually a 2022 pick, and is the better pick between the Nets and Heat).
From the Rockets perspective, this would give them a true point guard to put next to Jalen Green, and let them bring KPJ off the bench as a 6th man, which I think he'd be more suited to be. Plus it brings Fox back to Houston and lets the Rockets consolidate their assets , and to give more playing time to young bigs like Sengun, KJ Martin, and Garuba.
