Viewed from here, where American football remains, for most of us, a curiosity, this film about a doctor who challenged the sports-entertainment industrial complex behind the game is something of a revelation.
The fight that Dr Bennet Omalu took to the NFL over the long-term effects on players of the head-smashing game - those helmets only protect the skull, not its free-floating contents - wasn't front-page news as it became in the United States in the noughties.
It's engaging enough, especially with Will Smith depicting the Nigerian-born Omalu in one of the better dramatic performances of his career.
Smith is really good. In another year, he might have made the cut for best actor Oscar consideration - which would have had a nice symmetry with his previous nod, playing Muhammad Ali in the days before those blows to the head took their toll.
But the trouble here is, the virtuous, brilliant, Omalu pretty much is the movie. He's one heck of a whistleblower but it's just not much of a tune. And Smith's role becomes burdened by how much of it is spent bestowing a sainthood on the guy to accompany the many specialist medical degrees he has acquired before and after immigrating to the US.
Add a romantic subplot about his courtship with Mrs Omalu (Gugu Mbatha-Raw) and plenty of ponderings of the good doctor's own American dream and Concussion suffers an odd problem for a sports medicine movie - it fails to keep its eye on the ball.
There are some memorable supporting turns, especially from Alec Baldwin as a former team doctor attempting to make amends for sending so many concussed players back on the field and Albert Brooks as the mischievous but supportive boss in the Pittsburgh coroner's office where Omalu worked as a neuropathologist.
It was there that Omalu started his investigation after a post-mortem on a retired Pittsburgh Steelers player left him troubled about what had happened to the deceased's brain - which had left him in years of undiagnosed mental decline.
Concussion does attempt to say something about the NFL as an entertainment corporation. One which, before recognising the problem, was leaving as many as a quarter of its players brain-damaged and staying silent about it.
But the film seems to take its cue from the good doctor's even-temperedness. Just when you think it should be getting good and angry, Concussion goes curiously mild-mannered. As good as Smith's performance is, this feels like a fumble.
Cast: Will Smith, Will Smith, Gugu Mbatha-Raw, Alec Baldwin, Albert Brooks
Director: Peter Landesman
Running time: 123 mins
Verdict: Admirable performance from Will Smith as NFL head injury whistleblower can't save film.