Do contracts which have expired count? Because in that case I'd like to give TMAC an honourable mention. In terms of $$$ paid and games missed or games with crappy/injured performances, his gotta rank up there for being way overpaid.
Well... his max deal was actually well-deserved in his Orlando days, and it's not like you can just re-negotiate the contract once he got traded to Houston... Joe Johnson, while putting up a miserable performance... still got a max contract, when his market value was only like... 7-11mill...