National Basketball Association.
Major League Baseball.
National Hockey League.
What do these entities have that the National Football League doesn't? A minor-league system to help develop prospects and players.
The NFL at one time did have an offseason program called World League/NFL Europe/NFL Europa that allowed players who were fringe-roster types the shot to go and get some real game-time experience. Sometimes, even draft picks would be sent over after their rookie seasons sitting on the bench.
However, there is still not a true NFL minor-league system that has ever been in place. If the NFL wants to be a truly financially productive entity, they would look into a farm system that would allow call-ups and a season that ran very similar to baseball's minor leagues.
This slideshow will explore the idea of what would be considered an intelligent solution for an NFL developmental league.