It might be best to play Wemby at the 4 so that he doesn't have to battle down low against the Jokic's and Embiid's of the world, and the Spurs have a glut of wings anyways. So here they pick up a promising 5 who can solidify the spurs potentially elite defense with Sochan-Wemby-Allen as the front court, and also get a veteran PG to help everyone get into the offense and teach all the young players.
The Cavs get a long term answer at the 3 spot in Johnson who can form an insanely lethal scoring trio with Mitchell-Garland-Johnson, and Collins can stretch the floor opening up everything offensively.