The statistic depicts the average length of a player's career in the National Football League, considering different aspects influencing the length of a playing career. According to the NFL Players Association the average career length is about 3.3 years.umber of people who attended a National Football League event (USA), 2014. NFL event attendance: Number of people who attended a National Football League event within the last 12 months in the United States (USA) from spring 2008 to spring 2014 (in millions).