Festus Ezeli would be a good starting Center.
Very mobile for his position, improving offensive rebounder, can finally catch the ball, and now he's coming in to any team with championship experience.
It is an overpay, but I think this is a kind of overpay a team like the Lakers would do. He's young, and a proven quality player that would now get starter minutes. He's not going to live up to that contract, Festus is, as he's not going to score when you call a play for him, nor will he turn into an all-star, but he's going to do the effort plays, and do it really well, something that a team needs.
I think Ezeli will get that much on the open market. It will be interesting, because Ezeli getting that much will make it hard for GSW to keep him and Barnes.
I am just speculating on this, but there's no way GSW would bring Harrison Barnes back if he gets offered max or near max money. They've shown they could work without him, going really well with Brandon Rush starting. They have Kevon Looney sitting in the wings, and they have a draft pick this year that they could use to find a cheap replacement (their draft record since Bob Myers took over is exceptional).
I'd go as far as to say that I don't think they'll try to retain either if they get near max money. Ezeli is the heir apparent to Andrew Bogut, but seeming as Bogut looks like he can play for two-three more years, I doubt they'd retain him if he gets this much. They can just resign Mareese Speights and play him as the back-up Center and find a young guy to replace Ezeli's rebounding and defense, via the draft or free agency.