True, but players hire agents for the same reason you hire professionals.
When you hire a lawyer or a car mechanic, and they say This is what you should be doing, you tend to do it. When the mechanic says your Constant Velocity Joint needs replacing, do you say, No, it seems to me that it is the transmission, so change that instead?
Yes, the ultimate responsibiity is Deion's, but if he asked the agent for the best way to get a raise, and the agent says do this, it is hard to put the total blame on Deion for listening.
That said, I still think he (and/or his agent) is making a big mistake.