As a general rule, "overall" might as well be called "monetary demands" because that's that rating's biggest function. There are lots of cases where a 75 rated player will be better than an 85 rated player, but the 85 rated player is always going to ask for more money. It's programmed so that monetary demands are based on the "overall" rating. Overall can be a fair approximation of skill, but like everyone has said, individual ratings are the key.