Summer League isn't a real thing gents. It's obviously good news that he's looked good here, but it's summer league.
Fwiw with Graves specifically, he analytically boot fucked NCAA competition in his minutes, so he should look good at this level. His question in the NBA is whether his size and athleticism plays in his likely NBA role, and then whether his release is quick enough to shoot anything but wide open 3's. His IQ, effort level, connectivity, etc are all fantastic. That's what got him drafted.