Each year, the final salary cap figure flows directly from negotiations between the NFL and NFL Players Association. This year, it was expected that the salary cap would at least hit $178 million per team, with a strong possibility of exceeding $179 million.
Ultimately, the cap came in at $177.2 million. Per a source with knowledge of the situation, the lower-than-expected cap resulted from extra money being diverted to the Player Performance Pool.
The Player Performance Pool provides supplemental pay to players based on total snaps and standard compensation, via a formula that looks to reward lower-paid players who end up carrying a heavy workload. The good news, then, is that these overworked-and-underpaid men will get a little more extra than they otherwise would have.
However it shakes out, the money all ends up with players. Salary-cap money is distributed via individual contract negotiation; player performance pool money is earned.