Same. Of all the prospects I've evaluated in the last 15 years he might be my favorite. He had everything you want in a prospect aside from maybe elite athleticism but he was strong and smart so that didn't seem like it would be a problem for him. Elite defensive tools, he could pass well enough for a SF, he could handle and finish on the fast break, his shooting was respectable (37% at Arizona) so he should have been able to adjust to the NBA three point line in a couple years...
And he just never progressed
at all. Tobias Harris shot 30% at Tennessee, Kawhi Leonard shot 29% at SDSU. Both of those guys are shooters now and Stanley hasn't even come close to his college shooting splits. And by all indications he was a hard worker who loved to watch game tape. He was a proven winner in HS (the only player in CA history to start all 4 years and win a state championship all 4 years -- compiling an overall record of 135-5) and he won 3 gold medals playing for Team USA's junior teams in international comeptition.
Then he came into his first summer league and just beasted on everyone:
There's an element to this whole scouting business that I will never understand. No matter how perfect a prospect's resume and game tape, all of them are still works in progress and you just never know how that development is going to go. The only thing I can really think of that might have derailed him is that he was very close to his mom and she died unexpectedly before his rookie season started. That's a tough situation for a guy who dedicated his whole life to basketball and the single mom who raised him never even got to see him play in the NBA.