Associated Press

There is a scene in the movie Concussion—which I saw Wednesday at a sneak preview in Manhattan—where former Chicago Bears defensive back Dave Duerson and former Philadelphia Eagles defensive back Andre Waters get into a heated exchange outside the NFL's offices in Manhattan. The scene, quite frankly, brought tears to my eyes. I knew both men.

They were players who thrived on physicality, especially Waters. He was the hardest-hitting player I ever saw and, yes, the dirtiest.

Early in my reporting career, Waters once threatened to drag me out of the Eagles locker room and beat me senseless over an innocuous question I asked him. Waters would never blow up at me again. He was a gentleman. As was Duerson, always.

The scene from Concussion revolves around Waters saying something was wrong with him and he needed help. Duerson, on that busy street that day, rejected Waters' concerns, calling him weak. Not long after the confrontation, Waters would commit suicide, in 2006. Later, so would Duerson, in 2011. Duerson shot himself in the chest so he could have his brain examined.

George Gojkovich/Getty Images

Watching that brought tears and memories and, later, as the movie went on, pure anger. What Concussion does is act as a sort of demand for accountability, and the line of those being called to account is long. The NFL is the main villain, but the media (ESPN won't be too happy) and fans are exposed, too.

Michael J. Minardi/Getty Images

The movie—scheduled for wide release on Christmas Day—focuses on Pittsburgh pathologist Bennet Omalu's discovery of CTE and that in itself is an impressive story. But the movie's greatest strength is how it uses the tragic stories of Steelers Hall of Famer Mike Webster, Waters, Duerson and others to hold up a mirror to our football-crazed society, then and now. (The Steelers and the city of Pittsburgh will likely hate this movie.)

George Gojkovich/Getty Images

If you have a pulse and a conscience, the movie will cause you to examine this love of football, and at what cost that love comes to the actual human beings who play it.

"Playing football," Omalu, played by Will Smith, says in the movie, "killed Mike Webster."

Many in the NFL have told me they fear this movie. It's easy to see why.

The NFL is portrayed as a tobacco-style corporation that puts profit over lives. League executives are portrayed as shadowy and devious—at times, almost comically so, but nonetheless it's an accurate portrayal. Years after the death of Webster in 2002, it's become clear in hindsight that the NFL knew more than it let on and opted to, at best, ignore Omalu's findings. At worst, there was an attempt to bury the facts so as not to stop the cash cow that football had become.

"The NFL owns a day of the week, one the church used to own. Now it's theirs," one of the movie characters says.

Again, if you have a pulse, the actions of the league as portrayed in Concussion will cause great fury. The film will, temporarily at least, cause you to wonder how you can support the sport.

Kevin Winter/Getty Images

But the biggest threat to the NFL, and perhaps the movie's greatest accomplishment, is the mainstreaming of the neurological science. The movie explains, in simple terms, how the issue is not thunderous helmet-to-helmet contact but subconcussive hits. It explains how the brain sits in a fluid, disconnected from the skull, and how the trauma of football rips apart the delicate framework of the human mind.

Once people actually see this explained, and as that explanation becomes better-known, then that is where things will get interesting. This is also the part where the moviemakers force us to acknowledge this truth and grapple with it, no matter how uncomfortable it makes us.

This is football's Inconvenient Truth—the Al Gore movie that broke down global warming to a simple scale and evoked a better understanding of what was happening.

This is the best football movie ever made (and I've seen every one), because it does something that I like to do, which is pause and take a look around. I will go back to loving this sport, to playing fantasy football, to writing about the players, but for now, for right now, Concussion is causing me to look more closely at a sport we all adore.

And it isn't pretty.

Mike Freeman covers the NFL for Bleacher Report.