Since the start of the National Football League in 1920 it was considered a ruthless league with little rules or regulations considering athlete safety.  About 40 years ago the league decided to implement rules such as pass interference to limit unfairly contact upon wide receivers that didn't have the ball. In some instances players would be running into another as hard as they could not caring to hurt themselves or the opposing players, but the mentality of playing with injuries wouldn't stop players playing the game. There were many teams in the NFL that would strike fear into other teams such as the Raiders or the Steelers. These teams were feared because their main goal of their game was to go out and play ruthless football and to hurt the other teams best players. There was players such as Jack Tatum aka "The Assassin" that has paralyzed people, Joe Greene aka "Mean Joe" that has kicked opposing team players in the groin and has swatted balls from the line of scrimmage due to losing, and there is also Ronnie Lott whom cut off his pinky finger just to play in the 1986 season, this action is unheard of in this time of the sport.

"Jack Tatum"

"Joe Greene"

"Ronnie Lott"