I don't mind overpaying a really good player that addresses the biggest weakness on the team (wing defense). And the usage thing confuses me too, he's a really good passer (14.7% AST rate), he's was efficient with a 58% TS last year, he was effective at finishing at the rim with a 69.8 FG% on 179 attempts, and he got to the Free Throw Line at a good clip at .333. Everything points to him needing to be a more involved offensive player, but he just wasn't last year. Maybe getting him away from the iron fist of Pop will open his game up? I see no reason he couldn't be similarly effective at 18-20% USG.
This is the summer we can afford an overpay on a guy like Anderson, Smart, Gordon, Parker, etc. If we're serious about making a big win increase next year (8-10 wins), then we have to be aggressive on bringing a good young player who can grow with this core.