Axios

Thanks to an exploding NBA salary cap and a wild NHL postseason that saw many of the league's highest-paid players sent home early, the salary disparity between the two leagues has never been more glaring.

Like most professional sports leagues, the NFL focuses a ton of effort on finding and developing new revenue streams. But there's one resource that the league has yet to tap: jersey advertisements.

Why it matters: If every NFL team had a sponsorship patch like the ones you see in the NBA, it could net the league at least $220 million annually in added revenue — and that's an extremely conservative estimate.