reggie fleming... three of the four national hockey league players that we've studied that have had c.t.e. have been enforcers. the fourth one rick martin was not an enforcer. he had a mild form of it as well. reggie fleming, who died at a much more advanced age, had a very extreme amount of it. derek was just 28. the youngest of those in the national hockey league that we've had a brain to study. and the very fact that he had it, even at this more mild form it's a progressive disease so had he lived to be in his 50s and 60s, it would have been expected to be much more severe. >> brown: john branch, you quote in your story the nhl commissioner gary betman saying that it's too early to draw direct conclusions about a direct link between hockey violence and c.t.e. is that the state of understanding or acceptance of this... these links that you find in sports generally? tell us a little bit about that. >> sure. that's actually very similar to what the reaction was from the nfl a few years ago from the sam