I only saw the first game, but he looked super tired. I wonder if the altitude and speed of game is affecting him. In the first game he played 19min for 9 points and 5 rebounds and a plus-6. The second game he played 23min and was 6 and 6 with a minus-11. To be fair, besides Tatum, it looks like the whole team was trash the second game, including Brown. I also think there is a coaching discrepancy in the Summer League games when the assistant coaches take over. I think it was last year between Utah and Las Vegas, they were amazing in Utah and awful in Vegas after switching coaches.
I like Zizic, thought he looked decent against Philly. I'll wait to pass judgement because there are too many external factors at play.