"My determination as I go through each day is that some good might come out of his death," Brearley said. "That the research into brain trauma will somehow have more attention."
And indeed, doctors are now on the leading edge of discovering how young players like Owen Thomas -- with no documented history of concussions -- might have damaged their brains.
Researchers call these hits "subconcussive blows" -- moments at which the brain hits the inside of the skull, but not hard enough to sustain what a doctor would diagnose as concussion.
The question now is whether an accumulation of these lesser blows over time could cause brain damage powerful enough to lead to CTE, which has thus far mostly been documented in professional players with a history of concussions.
"How much of that is occurring? We really don't know," said Dr. Julian Bailes, Co-Director of the NorthShore Neurological Institute in Evanston, Ill., who has autopsied the brains of dozens of former NFL players.
"Several former football players who had CTE did not have a history of concussion, they didn't have it. But undoubtedly they had hundreds or thousands of head impacts through the course of their career," he said.
It's hard to know definitively who has CTE or at what point it develops, he said, because as of right now, doctors can only diagnose the disease post-mortem, by cutting open the brain.
So the question of what is happening to the brains of younger athletes looms. "I played football for ten years. I think it's America's greatest sport," said Bailes. "But I think we're at a little bit of a crossroads now."
"We need to continue to press forward with our medical knowledge, our sports medicine knowledge and make the game safer."
The key, according to Bailes, is taking head contact out of the game, especially for young people.
"I don't think they ought to have this potential for every play to hit head-to-head, what I call gratuitous, mandatory, obligatory head-to-head contact."
That recommendation is at the heart of changes he is proposing as the medical director of the Pop Warner youth football league.
"I think we'll really look at eliminating practice contact, particularly to the head. And I think that's an area that's been sort of overlooked, that we can immediately do, that will have a big impact," he said.