This deal was just completed in KuzForMVP's mock.
Knicks GM: Me (Paolo4MVP)
Cavaliers GM: theswagduck
Why the Knicks do this:
I'm the Knicks GM and I'm not high on RJ Barrett. I don't think he will be an All-Star in this league, and I am trying to rebuild. I consider this offer to be too good to pass up, mostly due to the picks. LeVert is also solid, and Okoro still has some potential.
Why the Cavs do this:
I suppose theswagduck did this because he thought Barrett would be a great SF for the Cavs. For more details, you'll have to ask him.