Hockey is a sport filled with players focusing on a specific role on the ice. Some players are there to shut down the other team's top scorers. Others are a team's offensive lifeblood.
Football is similar to hockey. Each player on the field has a job to focus on, and try to accomplish their job to the best of their ability.
This list isn't necessarily composed of players who could play in the NFL, but whose style of game translates to that of various positions on the gridiron.