Doesn't have to and we could afford him very easily, as has been pointed out. Players covet guaranteed money (not what an agent tells you how much guaranteed money is in a contract), I mean what the signed check is in front of them, because all those other numbers can go put the window quick. So if the Cards really want KC their going to have to cut a very large check, as his signing bonus, likely around 60 mil. Then you spread that 60 mil over 6 years that is 10 mil plus his salary which could be say 5 mil, his cap hit for the first year is only 15 mil. The next 4 years his cap hit would be 30 mil each year (paying him 20 mil a year) and a whopping 45 (paying him 35 mil) in the sixth year at which time you redo the contract or you simply let him go with a dead cap hit of 10mil. 6 years 180 mil and he is the highest paid player in the NFL for a week or two...
The real thing is most of that 180 in somewhat guaranteed because of the sever cap ramifications in the scenario I laid out. I am sure some cap guru could structure it much better to get it where they could get out it sooner without as much damage. I just wanted to lay it out where he could be a Card and only count 15 mil against the cap next year. He still make 85 mil or his 180 total in the first 2 years.