I spent a season watching Barnes be terrible regardless of his minutes.
Barnes was not "good" his rookie year. He was just somewhat competent for a rookie, with a decent run in playoffs because every coach literally gameplanned to allow Barnes to post up on PGs rather than let Curry shoot the ball. Somehow he regressed, and I will say much of it was due to him being run in Mark Jackson's benchmobs. However, if he was a star, he would manage to distinguish himself, especially playing against other benches.
So I did:
Draymond Green had 21.9 minutes per game.
Barnes had 28.3 minutes per game.
That is MORE than he had in 2012-13 (25.4 per game). That is more than Andre Bogut. And that is just 4 less than Iguodala, against weaker competition.
Barnes shot .399% FG. That is abysmal with plenty of court time, much of it undeserved.
Barnes got his minutes. He just wasn't very good. Poor basketball IQ, poor creator, poor motor, poor lateral speed (his footwork on the perimeter is terrible-- he starts out spread legged and gets no displacement on his first step), poor ball handler, inefficient midrange shooter, poor rebounder for his size. He's an average defender and not a very good scorer who's especially terrible in isolation. I think he could pick up his shooting since he has good form, but in no world is Barnes even remotely comparable to Green. Physicals are often overrated as "ceiling", but the mental aspect is just as important and sometimes more elusive.
Now I'm still rooting for him, and I think his lack of role definition contributed much to his regression, as well as a possible foot injury and lost confidence-- but no sober basketball analysis can say that Barnes wasn't good only because he wasn't getting minutes, or that he's as valuable player as Green.