There's some irony here: The man who maybe has done the most to bring a hot-button issue to public attention - the later-life dangers from repetitive football hits - isn't in the film that will give the issue its greatest public attention.

The first thing I did on hearing Concussion the film was coming out was to check the cast list, to see who was playing Chris Nowinski.

Answer: nobody.

Obviously, storytelling requires tough decisions to keep the story moving. Concussion spotlights a crucially important figure in this whole saga, Bennet Omalu, the Pittsburgh pathologist then working at the Allgeheny County coroner's office who had studied the brains of two deceased NFL stars and found massive trauma. The paths of Nowinski and Omalu intersected when Nowinski - a former Harvard football player and professional wrestler who had become a concussion activist and written a book in 2006 called Head Games: Football's Concussion Crisis - got permission to study the brain of former Eagles player (and legendary hard-hitting safety) Andre Waters.

There is a Waters character in the movie. Waters had committed suicide in 2006. In a 2010 interview, Nowinski described for me how he had written out a script to Waters' family, believing that if he said one word wrong - "if I PAUSED wrong'' - the answer from Waters' family would be no to his request to study the brain.

Nowinski had remembered Waters' heavy-hitting Eagles reputation. He had read how Waters once told an Inquirer reporter that he'd stopped counting at 15 concussions. Nowinski knew Waters was only 44 years old at the time of his death and had been working as a college football coach after his playing days.

"There's got to be something we're missing here," Nowinski told me in 2010, of working to get Waters' brain to Omalu to study.

Nowinski is in the exhaustive GQ article that the movie is based on and the article explains that Nowinski and Omalu soon went on different paths. It suggests the parting was over Nowinski's belief in the need to make the issues more public.

Nowinski joined forces with Robert Cantu, a Boston-based concussion expert. They then teamed up with two researchers at Boston University, Robert Stern and Ann McKee, to establish the Center for the Study of Traumatic Encephalopathy.

Earlier, by the time Omalu found CTE in Waters' brain, the National Football League had to deal with the issue.

"It was on the front page of the New York Times," Nowinski said in 2010.

Reached last week, Nowinski said he hasn't seen the movie and didn't really want to say anything directly about it. Asked about his split with Omalu, Nowinski said, "The truth of the split has never been told.'' He said he made the right choice. "I said, 'Look, let's work with more people.' "

That work continues. The group of scientists in Boston has studied "somewhere over 300 brains,'' Nowinski said, and "in the ballpark of 175" have been found with CTE. Obviously, that is a self-selecting group of brains. Still, the findings are eye-opening.

"The clear relationship we seem to see with trauma is its close relationship with the facts that the earlier you start, the more times you get hit in the head, the greater the risk,'' Nowinski said last week.

Again, the tale of Concussion is important. Omalu's work was the genesis and his work continues. The moviemakers picked the right character to focus on. And for Hollywood to have portrayed the rest of the story, the movie would have needed to be 10 hours. But there's a sequel to be made and the central character might be a former pro wrestler who also dedicated his life to this issue, and began with a phone call to the family of a former Eagles star.