Of course you would. Kirk's getting about $10 million less than that, this year, but even with that you'd still take Mahomes. That's not the point, though.
Patrick Mahomes has the largest cap hit of any player in the NFL, this season, at just under $40 million. Does he deserve it? Absolutely yes. He's earned every penny. But as a portion of the salary cap, this year, he's counting for more than any other player. And that cap number goes up in following years. His cap number is going to be top 2-3 in the league for quite a while. Is it less than he could have gotten on the open market? Yeah, that's very possible. But as it relates to impact on the cap, it's not really much of a discount. At least, it's not giving the Chiefs much of an advantage on their cap, as compared with other teams.