Two scenarios I see with Barnes.
1.) He underperforms this season and becomes a bit of a gamble but gets slightly overpaid thanks to the GS luster.
2.)He meets or exceeds projections of player growth and he gets a max thrown at him and GS either maxes or lets him walk(they have already made it clear they probably let him walk)
He is going to get overpaid either a little or a lot.....Or, the unlikely third scenario, he is going to develop into a true max quality player and we are in a persuasion war with other teams to accept our max and hoping GS doesnt change their mind and match.
The only way I would really want to chase him is if he just blows up this season and passes all the eye tests and analytics of the experts so we have more comfort we aren't just getting a player being given a false sense of greatness because of his spot on a great team.
I would love to have him as our SF but cost and opportunity cost really matter here.