the only conclusion i can come to is that the kings have to take on a good amount of salary to make sure they are at the minimum salary cap, which was raised in the new cba. they were barely at the minimum in the prior CBA when it was a good deal lower. still doesn't make much sense overpaying for a role player as limited as chuck hayes, though.
I think this is exactly the reason they signed Hayes to this type of money -- they actually HAVE to to meet the min. salary requirements in the new CBA.
That said $5M/ year for 4 years isn't that bad for the Kings for a guy like Hayes IMO.
First, as someone else mentioned he'll bring some veteran grit to a very young frontline.
Second, contending teams (who ostensibly are more likely to take on a questionable contract) will, or should, always be lookign for team-first, solid rebounding guys like Hayes. I see him as cut from the same cloth as guys like PJ Brown, Robert Horry, etc. Guys who will do the little things that help teams win titles.
In 2 years Hayes' contract will be $10M/2 years and the Kings, if need be, can easily move that.