You can absolutely learn things from summer league play, but its not about the stats. You look for skillsets. See what a guy can and can't do. he may miss his shots, he may be out of shape, whatever. but skills are skills, and if a guy, even once, drops an open court crossover into a spin move while throwing a no look pass to a 3pt shooter in the corner...well he didn't just get lucky. Also a good place to check out relative size and athleticism away from the wearing shoes or not/what league was he in nonsense.
What you can't do is say ooh! ooh! Player A averaged 25 a game, while Player B averaged 12 a game, Player A > Player B!
This summer league has revealed that:
a) Skal flat has skills all across the court. He can shoot threes, he can post up, he can handle the ball. An impressive skillset. You won't know if it will translate, but he's the find here.
b) Malachi is bigger/stronger/longer than you would have expected, and he looks to have real potential defensively (possibly why this regime even took him) and with physicality. He's not just a perimeter shooter. He gets into guys.
c) Big Papa flat lacks 1 on 1 skills right now.
d) WCS is the greyer area, because it was obvious that he was unfocused, uncomfortable in his role, and missed everything as a goto guy. But he made moves that looked coordinated, he just couldn't finish them. That's more than some could do. His fluttering about on defense and the glass would be a larger issue if we hadn't already seen him for a year in the NBA.