Yes, yes, yes and yes. And not even because I think all or any are max players. It's the talent pool of the NBA is limited to around 120 impact players. Because of that you have to overpay for any top 60 talent.
Derozan is more proven. He is Turner X2 as far as game impact and we see what Turner does here. Double his play and that is Derozan.
Whiteside and Drummond are in the small group of Howard, Davis, Drummond, Chandler(2 years ago), Jordan, Ibaka (preinjury) and Duncan as far as paint defense with some offense. Their offense is of course lower than some I named but the D is there or better. That has to be worth max $ to someone especially a team like C's.
Barnes is in that Hayward to Harden mold. Sure he doesn't look like a big time player but he has all the tools to make a big leap. It's a bet a lot of teams are willing to do to get that kind of player if at all possible. At worse he has Parson level impact.
So blame it on the talent pool but all are max guys in today's NBA.