Knicks move for fit over talent. Not much to explain, but a lot to get over.
Hart is really good, better than Champahnie and Kispert by a good amount. But, the parts of the game he struggles in are the kind of things the knicks really need(mainly being 3 point shooting and size).
So here, the knicks part 2 Hart plus some draft capital(effectively 4 seconds) for Corey kisper and Champaigne. Imo Kispert is an ideal 6-7 man. Great and willing shooter. Decent with the ball in his hands. Has size but is... well a bad defender. Champagnie shot the 3 great last year and is a solid defender and rebounder(and hes still young on a great contract). Now, there is a chance that both kispert and Justin are overperofming on a bad team, but theres also a chance they will excel in more defined roles. I think that the shooting both these guys provide and Champagnie's defense and rebounding cover Hart's strengths, and it may be a worthy gamble for the knicks.
Wizards do this for the draft capital(control of their own pick) and to focus on the young guys(being Sarr, bilal, bub, kyshawn, and whoever they draft). Hart likely gets moves for more either right away or at the deadline.
Knicks would either start champaigne or Mitch, and then bench would be some combo of basically any of the guys on their bench depending on rookie development. For now lets say its Deuce, Kispert, Nance, Mitch/Champagnie with guys like Pacome, Hukprti, and Kolek all getting looks thru out the season