This is one of the toughest things about the game of football, really. In my humble opinion (although I'm not a doctor), I really believe that it's the full responsibility of the medical staff to keep this kid (or any kid) out of the game if there is even a doubt that he is not okay! The coaches are always going to default to the decision of the medical staff. If they get the "thumbs up" from the medical staff, they are going to behave like everything is okay and it's business as usual. It seems clear now that it wasn't "business as usual" for Chandler, and the medical staff should have known as much...