Cam Newton lay motionless, a rag doll tossed to the ground.

The reigning NFL MVP tried to get up, but his body failed him. All Newton could do was roll over and clutch his helmet.

It was the NFL season opener in early September, and the Denver Broncos defense had just bashed Newton in the head again, one of many helmet-to-helmet hits on the Carolina Panthers' quarterback that night. Medical staff members — trained to spot head injuries — reviewed the play and went through the league's concussion protocol.

Then, they made a decision, one that was questioned by many, including the NFL Player's Association.

They let Newton keep playing.

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After the game, many wondered if the Panthers had, in fact, followed proper protocol. And as it turns out, the NFL investigated the same thing.

The league announced Wednesday it would enhance its concussion protocol after the confusion surrounding Newton's helmet-to-helmet hits in Week 1.

The NFL says its spotters saw "no indications of a concussion" for Cam Newton: https://t.co/2DVhLPnkVL pic.twitter.com/Xx5zMPBpZs — SB Nation (@SBNation) September 9, 2016

Here's what actually happened that night, according to a statement from the league.

Sideline medical staff members contacted a concussion spotter in the booth for video of the hit on Newton, but a technology glitch delayed that process. Under the league's concussion protocol during Week 1, once that contact was made, the booth spotter lost the ability to call a medical timeout. The sideline medical staff made their own assessment of Newton — without video from the booth — and let him play on.

The new protocol requires the booth spotter "to remain in contact with the club medical team and provide video support until the medical team confirms that a concussion evaluation has occurred," the statement said.

Image: Denver Post via Getty Images

The league has periodically made changes like this to the concussion protocol since implementing it in 2009.

That's largely because as public discussion about head trauma has increased in recent years, the NFL got into some hot water.

In 2013, a pair of ESPN reporters published League of Denial: The NFL's Concussion Crisis, a book/documentary film exploring the link between the sport and brain injuries, and the NFL's reluctance to acknowledge that link.

Some have accused the league of trying to cover the problem up.

According to the New York Times, the NFL's own lengthy concussion research studies left out more than 100 diagnosed concussions. The league finally admitted the connection between football and brain injuries in March. A month later, an appeals court approved a class action settlement between the NFL and thousands of retired players, who received varying levels of compensation for dealing with repeated head trauma.

So — as part of that ongoing safety push — the NFL announced in September that it would commit $100 million to concussion prevention initiatives. Before this season, it added stricter enforcement of its concussion protocol — teams can be fined or forced to forfeit draft picks if they violate it.

With such a sensitive and complex injury, the specifics of concussion protocol are necessarily and equally complex.

They also remain a topic of conversation among hardcore and casual football fans alike. Donald Trump mocked the league's player safety procedures at a campaign stop in Florida last week, when a woman in the audience attendance fainted and then returned to the crowd.

Woman faints, gets back up, then Trump bemoans "softer NFL rules" — "Concussion, oh! Oh! Got a little ding on the head—no no you can't play" pic.twitter.com/hdOHKiJmBQ — Bradd Jaffy (@BraddJaffy) October 13, 2016

"The woman was out cold and now she's coming back," Trump told the crowd. "See? We don't go by these new and very much softer NFL rules. Concussion, oh! Oh! Got a little ding on the head, no, no, you can't play for the rest of the season. Our people are tough!"

Obviously, the rules are not that simple.

The league released a detailed description of the game-day process on its "Play Smart, Play Safe" website in September, but here's a stripped-down version:

When a potential concussion is identified, the player is removed from the field. The medical staff reviews video of the play and performs and an examination. If the medical staff suspects a concussion, the player is taken to the locker room for a full assessment. If the player is diagnosed with a concussion, he can't play that day. If the player passes the exam, he will be monitored for symptoms throughout the game.

When players are removed from the game with a concussion, as Cam Newton was two weeks ago, there's a multi-step progression for returning to action as well, which includes rest and recovery, light aerobic exercise, strength training, football activities and then full clearance.

Newton missed Week 5 because of concussion he sustained in Week 4 against Atlanta. Image: Kevin C. Cox/Getty Images

While it's encouraging to see tweaks to concussion protocol, some see the NFL's player safety push as an empty promise.

None of the Week 1 helmet-to-helmet hits on Newton resulted in penalties, which led many — including Panthers' tight end Greg Olson and Newtown' dad — to criticize the NFL for not officiating with safety in mind.

"Player safety sounds great, is a great offseason rallying cry, sounds awesome," Olson said. "But we got zero yards out of any of those hits. That’s the reality of it.”

In the statement from the NFL on Wednesday, the league lauded referee Ed Hochuli for following protocol and removing Buffalo Bills quarterback Tyrod Taylor from a game. The league said it would use Hochuli's "proactive officiating" as an example to other referees.

Image: sbnation

Seattle Seahawks cornerback Richard Sherman blasted the NFL earlier this month for its shoddy relationship with players, particularly when it comes to safety. He called the league out on what he says is a hypocritical push.

"It's hard to stress player safety in such a violent game," Sherman said in The Player's Tribune. "Does the league care when Cam Newton gets hit in the face five times and pretty much knocked out the game? They have all these spotters and people that watch the game specifically for these reasons. You see the guy on his hands and knees shaking his head after he just took a shot to the face, and they're saying they didn't see any indications that he needed to come out of the game."

The NFL cares more about ratings than safety, Sherman said, so taking a star player like Newton out with the game on the line could have damaged those ratings.

But Newton's case represents a larger discussion among players, who feel like the league doesn't take care of its assets.

"It’s a huge issue — one that a lot of players talk about behind closed doors, and would like to talk about more openly," Sherman writes. "They’re passionate about it and they want to see change."

As of Wednesday, there is change.

But don't be surprised to see critics from within and outside the NFL call for more progress. For a league that owes $1 billion to settle thousands of concussion lawsuits, this is an issue that won't go away overnight.

The Associated Press contributed to this report.