It actually makes perfect sense for the Wizards.
A roster full of scorers and a big man that needs a PNR parnter.
Trae has many flaws, but he's elite at running the team and getting everyone involved.
Sarr is their franchise player and he'll be the biggest benefactor of this trade. I expect him to be the best big in the East in no time.
Trae is the only non-rookie contract they have after this trade, they have to pay someone. He'll decline the option and either get a 3 year max or a bit cheaper, but longer deal.
Perfect to bridge the gap between them being one of the worst teams in the league and a solid playoff team.
Then when they're ready to contend, they'll move on from him.
They just need to have some lottery luck and get one of those wings in this draft and they're good to go.