In American football, each team has 11 players on the field at one time. The specific role that a player takes on the field is called his position. Under the modern rules of American football, teams are allowed unlimited Lineman · American football strategy · History of American football. Whether on an offensive or defensive line, each player in a football lineup has a specific job to do. Each player/ position has a specific role to play. The offensive. There are many football positions who have obvious roles, like the quarterback. But when it comes to telling the difference between the fullback and running.