In the battle for dominance in American sports, the NFL is Achilles – a great warrior destroying all challengers. It eats up the largest percentage of coverage on SportsCenter. Through July, all 10 of the year’s most watched sporting events were NFL games. Among the world’s 50 most valuable sports franchises, 30 come from the NFL. Fantasy football, a massive driver of interest in each week’s games, is a billion dollar business with over 32 million players. According to one estimate, the near-constant search by the American worker for injury updates and waiver wire diamonds costs the economy upwards of $6.5 billion a year.But even great warriors aren’t without weakness; Achilles had his heel.The NFL has the head.Awareness of and sensitivity towards concussion and other forms of mild traumatic brain injury (MTBI) has skyrocketed in the last decade. The league has overhauled its concussion protocols, implemented several significant rules changes designed to protect a player’s head, some more enthusiastically greeted by players and fans than others, all done in the shadow of recently settled litigation by over 4,500 former players against the NFL who say the league misled them about the dangers of head injuries and their cumulative effects. Several…