I assume Pop bc a lot of these guys, the first round picks especially play a different ball when young. They are talented enough to be top players in their youth teams and in their college teams. Even in the dleague they stand out. You send them to summer league and they stand out. In all those teams they play with the ball a lot bc they are frankly the best players in any of those lower leagues but the NBA is a different animal and you can't play youth ball or dleague ball there.
You have to play differently. Part of it is,if Pop doesn't play them regularly it's thought to learn any consistency. Not enough reps, not enough against good compe ion etc. The other part is correcting guys when they do play, teaching, which is why all these coaches have an easier time playing vets. The young players do need to play in a different league, and off their leaders. I don't see enough cutting and screen setting inn the young players except for Kyle, who has adapted to playing off the ball and is always setting screens off the ball, cutting and/or sending others to cut. MAny of the other are just standing around when someone else has the ball. It's been a pet peeve I have had for a while.
But you mention a good point in that if players can't pass the ball well like LMA (who can't) then others aren't that active off the ball bc they aren't going to get the ball. Lack of talented passing is an issue in the SL at times. In general though the younger players tend to not be active enough cutting or screening off the ball.