that changes the game to me. >> wrapped up and brought down by owen thomas. >> narrator: because he'd never had a diagnosed concussion, drd thomas might have gotten cte from the everyday sub-concussive hits that are an inherent part of the game. >> another nice play by owen thomas. >> those sub-concussive hits, those hits that don't even rise to the level of what we call a concussion, or symptoms, just playing the game can be dangerous. >> the rock is home. a crucial matchup in the afc... >> mckee is saying, "look, this is very much an issue at the core of the game, of offensive linemen and defensive linemen pounding the crud out of each other..." >> (grunting) >> "...on every single play, on every single down at every single practice, and there's no getting around that." >> narrator: it was a controversial theory that raised fundamental questions about the way the game was played. >> the human body was not created or built to play football. when you have force against force, you're going to have injuries. and i'm not talking about the knees and, you know, all of that stuff is a given. but from a neurological standpoint,