1 game is obviously not enough but if you go back to last year the development isn't really where anyone hoped after that great rookie year.
Things I liked about that single small sample game: overall aggression, attacking the basket, relatively few midrange attempts, good opportunistic rebounding
Things I didn't like: the ball sticking seemingly every time it came to him (and Kemba), forcing shots in lieu of ball movement, bad turnovers, not getting to the line much (and missing 2 when we needed them), some defensive lapses
Tatum+Kemba: 12/40 from the field
Rest of starters: 16/29
It's reasonable to be a little irked at how those two played, even if we don't want to extrapolate too much from it.