CAR already paid the bonus money.
That is his total cap hit starting next season according to wgr starting next season.
https://www.spotrac.com/nfl/carolina-panthers/christian-mccaffrey-21749/
Assuming CAR even eats 3/4 of that (restructure then trade him) There is still Hyde, poyer, Edmunds, Oliver and Davis coming up over the next two years.
Should the Bills drop 5m/y on a guy that is going to get 9 touches per game or invest in the others I mentioned?