In that light Seau, who never had a diagnosed concussion but played 20 seasons as a battering-ram middle linebacker, is probably the least surprising CTE case in the history of football. If this is a tipping point, it's only because of his Q rating; we were already there as far as the science. The urgent need is to study what doctors call the "dose-response" relationship between hits and brain problems—the connection between the number and force of hits and the specific damage to the brain. "That's been neglected," says Guskiewicz. "It can't just be 'got [CTE] or don't got it.' My guess is you and I probably have tau protein somewhere in our brain. A little may mean nothing."
Once we know how much tau is too much, the next step is to couple that with real time detection, looking at the brains of living former players. In a study published by the Journal of the American Medical Association three days before the Seau/CTE news, researchers used imaging technology that shows the flow patterns of water over the brain to detect damage to cerebral white matter in former players who are cognitively impaired.
At this point, it is pretty much a given that the dissected brain of someone who played football for a living and had cognitive impairment will show tau protein. But it's up to the scientists, rather than writers, broadcasters and pundits, to determine the connection between head hits, brain injury and damaged lives. Until that becomes clearer, talk of a tipping point is meaningless.