This doesn't make much sense to me. The Cs have already passed up one offensive stud who sometimes isn't totally focused on defense and lacks explosiveness in Fultz. I don't know why they would then go for the second fiddle in Tatum.
Jackson makes far and away the most sense -better fit with Hayward, more potential, and better asset. I don't know that he will be the better player, but the Cs are in a position to take that chance.