I think Tatum will be fine. It seems to me he is treating these games like they don't matter (they don't), but that's not really the level of 'excitement' you want to see out of a 3rd year player. I am hoping he's not just simply PO'd that he has to be away from his son and is forced to play basketball again.
Once the games mean something, he should conceivably go into lethal Tatum mode once again. Also, getting back into basketball shape takes a little time. Wasn't he singled out as a player who hadn't touched a basketball for months?