The deal with spreading the cap hit over five years, is the cap increase around 10% per year(another formula).
Soooooooooooooo if the cap is 150 this year and 225 in five years, the 20 million in the future is a lower cap hit due to growth.
It's just another layer and the saints used that method to a master class with most of the contracts while Brees was passing for 5k.