He’s too busy splashing on CP-3 and Beal.
There’s an ESPN video of them going one-on-one. Tatum is showing off some moves to get Separation and taking it to the rim. He doesn’t stop anyone on defense, but these are offensive highlights, and he’s keeping his hands up and staying engaged and in front of guards, which is a big improvement from last year if he can play like that in a real game.