Broncos linebacker Von Miller details his strategy of going after the quarterback while being mindful of the new rules in place to help protect QBs. (1:29)

A rousing start to the NFL season has all but buried an offseason packed with storylines on concussions and the rule changes designed to prevent them. Over 32 games, officials have called just two penalties for lowering the helmet to initiate contact. The reimagined kickoff has produced a higher touchback rate relative to last season -- but also longer returns on average. And there have been only isolated complaints and anecdotal stories about an NFL/NFL Players Association decision to ban 10 underperforming helmet models.

Those developments have returned the focus largely to the field, where scoring is up and quarterback efficiency has never been better.

In reality, it will be months before we know whether the NFL's 2018 "call to action" on concussions will produce a tangible result. What is clear, however, is that the league will press on with a new process that has dramatically altered its football decision-making, a method that has set the stage for further changes at a pace unheard of for an otherwise plodding league monolith.

The 2018 kickoff and use of helmet rule changes were based on data gathered as part of a $60 million partnership with biomechanical engineers who presented what the league's competition committee considered incontrovertible and objective justification for action.

"The kickoff rule and the lowering of the helmet rule are changes made by the competition committee because they were infused by a level of data and a level of expertise that it didn't have available before," said Jeff Miller, the NFL's executive vice president for health and safety. "It was heartening that the committee accepted it so openly. It said, 'This is very important information and let's do something with it.' It's a process we'll continue to use moving forward."

The NFL has a complicated and often lamentable history with the brain health of its players, and some of its current efforts to fund brain studies have drawn skepticism. And the league carried out its "call to action" -- a phrase first voiced publicly by the NFL's chief medical officer Dr. Allen Sills last February in response to 291 documented concussions in 2017 -- with almost no public mention of chronic traumatic encephalopathy (CTE), a debilitating brain disease that can cause a range of symptoms including memory loss that Miller has said is linked to playing football.

Regardless, the league is plowing ahead with the information to tailor its rules to the source of brain and spine injuries.

Saving the kickoff

To understand how the NFL effected a pileup of rule changes this year, it's worth recalling how it once made the decisions that shaped its on-field product. In 2009, for example, the NFL thought it had made a change that would lower the incidence of serious injuries on kickoffs: The league decided after years of discussion and debate to outlaw wedge blocks involving three or more players on kickoffs. (A wedge block occurs when players come together shoulder to shoulder and advance together to block the cover team.)

Why did the competition committee exempt the two-man wedge? Because, committee chairman Rich McKay said, it felt compelled to compromise with coaches who theorized that returners would be left without adequate blocking and thus put at a greater risk of injury. At the time, the committee made decisions based on subjective analysis of tape. It had no data to refute the coaches' contention and was unlikely to get the rule passed at all without giving in.

The NFL outlawed wedge blocks using three or more players in 2009. AP Photo/Rogelio V. Solis

In retrospect, McKay said: "I'm not so sure we should have listened to that." The move failed -- by the end of the 2017 season, the kickoff still was by far the most dangerous play in football. As owners and league executives pondered eliminating it altogether, the competition committee in March heard a presentation from Sills, Miller and Dr. Jeff Crandall, a biomechanical engineer from the University of Virginia.

Crandall and his consulting firm, Biocore, had been working with the NFL since 2006, at first focusing on lower-extremity injuries. Crandall joined the NFL's Head, Neck and Spine Engineering subcommittee in 2015 and was charged with creating an "Engineering Roadmap" -- a long-term plan to reduce injuries with a special emphasis on concussions.

To assist, the NFLPA hired Kristy Arbogast of the University of Pennsylvania and Barry Myers of Duke University, both biomedical engineers. (The NFLPA did not respond to requests for comment on the league's offseason action plan.) The NFL backed Crandall with about $60 million of its $100 million investment toward its "Play Smart, Play Safe" initiative. By the winter of 2018, Biocore had built models from studies of a majority of NFL concussions that had occurred during the previous three seasons. The answer to the kickoff question seemed clear.

Two out of every three concussions on kickoffs occurred when using a two-man wedge, a technique still legal under the 2009 rule. It wasn't merely a violent block, Crandall's presentation showed. The wedge technique encouraged the use of 300-pound linemen to block much smaller players who were running at speeds of more than 20 mph. The resulting force levels, documented on simulation after simulation via computerized stream, were unseen in any other part of the game.

The two-man wedge "jumped out," McKay said. "There was no guesswork anymore. We had to get the big bodies off the field."

Crandall's data showed the size of players involved in the collision was a driving force in kickoff concussions. A collision between a free runner and a returner, as a matter of physics, would be less forceful than a free runner and a 300-pound wedge blocker. There was little to refute when two-thirds of concussions suffered during kickoffs came when a single technique was used.

"There wasn't a group we had," McKay said, "that once they saw presentation and saw the numbers, didn't say, 'OK, I get it.'"

Into the modern age

In all, Biocore found credible and specific causes for 459 of the 600-plus concussions it studied between 2015-17. It mapped about 150 data points that included the position of the body, the forces involved, impact source, the location of impact and the type of helmet. Most of the raw numbers came from RFID chips installed in every player's shoulder pads.

Crandall's team then searched for trends, especially as it related to the performance of helmets, which are primarily designed to prevent skull fractures. Research has long shown that rotational forces, not blunt impact, were primarily responsible for concussions. CTE is believed to be caused by repeated subconcussive impacts.

While some experts warn that redesigning helmets won't meaningfully reduce concussions, the NFL hoped Crandall could provide guidance on improving current equipment and spark industry innovation.

According to Crandall, Biocore used its data to model the most common actions that led to the concussions between 2015-17. It then simulated the action on 34 helmet models in its lab, applying the action to a helmet affixed on a crash test dummy, to measure how well it handled two forces: the rate of rotation and the acceleration of rotation. The lower the level of forces that reached the "head" of the crash test dummy, the better the helmet's composite score.

A cross-referencing exercise revealed that the poorest-performing helmets also had the highest incidence of concussions on the field. That correlation prompted the NFL and NFLPA, for the first time, to ban the 10 models with the worst scores. The tests covered virtually all of the helmet models in use by NFL players, and the ban forced about 200 players -- including Drew Brees and Tom Brady -- to change helmets either immediately or by the start of the 2019 season.

Officials have called penalties for the new helmet rule just twice during the first two weeks of the regular season. Curtis Compton/Atlanta Journal-Constitution/AP Photo

Beyond helmet performance, another trend to jump out to Crandall's team led directly to the 2018 helmet rule: The incidence of concussions involving helmet-to-helmet hits had risen from 33 percent in 2015 to 46 percent by the end of last season.

"So we said, 'Let's take a further look,'" Crandall said. "What's the behavior behind this rise? We started to examine the videos. What we saw is the number of impacts that were occurring where players were lowering their heads."

Football players have long been taught to keep their heads up and "see what they hit" to protect themselves from neck injuries. But when Biocore examined recent concussions, it saw a relevant pattern. Players were dropping their heads, straightening their backs and in essence adding mass to their torsos.

That position "dramatically" increased the force of contact, according to Sills. Most visibly, it produced catastrophic results last season for Pittsburgh Steelers linebacker Ryan Shazier, who suffered a severe neck injury last December and won't play this season.

"When you lower your head and lead with your head," Crandall said, "and you line up your neck and torso, you recruit all of the mass of your torso. So you're really providing the opposing player much more severe of an impact. From a biomechanics perspective, this is risky for the player that is getting impacted and also risky for the player that is exhibiting the behavior."

After hearing from Crandall during a January competition committee meeting, McKay gave him a new assignment.

"We said, 'Go back, look at these plays and tell us if we had this rule, and they couldn't use this [technique], what's the impact?'" McKay said. "And the results were substantial." In fact, Crandall said, there was a direct correlation between the degree of lowering the head to initiate contact and the risk of concussion. From an objective observation, Crandall said: "Reducing the frequency of players lowering their heads will help prevent injuries both to themselves and the collision partners." And thus the helmet rule was born.

Crandall's job is limited; he provides data and analysis to produce an accurate snapshot of injuries and how they happen. It remains up to McKay and the rest of the competition committee to translate that information into practical rules. Public uproar over initial preseason enforcement of the helmet rule, coupled with a dramatic reduction in flags during the first two weeks of the regular season, suggests the committee has more work ahead of it to find realistic ways to avoid lowered heads.

"This isn't just a mathematical prediction," McKay said, "and some algorithm spitting out, 'If you do this, this is going to be the result.' This is actually watching the tape that has every single injury on it, and an explanation of who got hurt and how. That's where all of a sudden, the light goes on to you, whether you are a coach or a GM or an owner, which is all the types that are on the competition committee, the light goes on and you say, 'We can impact this.'"

In either event, Crandall's work has helped spark a necessary streamlining of health and safety discussions. Without it, McKay said, the kickoff and helmet rules never would have passed without first undergoing years of testing and evaluation. "What would have happened is there would have been much more debate," he said, "and much more public discourse. There would have been much more complaining during the process, concern about the future of the game, people saying, 'Hey, can we modify the language?'"

The data didn't necessarily change any instinctive thoughts, said Pittsburgh Steelers coach Mike Tomlin, another member of the committee, but it did help reinforce some intuition.

"All information is good," Tomlin said. "But we can't rely on data alone and we didn't in this instance. We always look at the video, and the video is telling. But make no mistake, data is awesome support and a significant element of the discussions."

Moving forward

The NFL adopted the kickoff rule for only one year, meaning its impact on concussions will be evaluated after the Super Bowl. Its on-field influence has been mixed.

Hopes for more and longer returns haven't completely materialized. The touchback rate actually has risen 9 percent compared with the first two weeks of 2017, from 62.5 percent to 68.1 percent. But of the kicks that have been fielded, the average return has increased from 22.1 yards in Weeks 1-2 last season to 24.7 yards in 2018.

The helmet rule is permanent but also will be evaluated and possibly tweaked in 2019. Referees threw an average of 1.55 flags for it per game during the first two weeks of the preseason. That average dropped to 0.625 per game during the final two weeks, and the near-disappearance of the penalty during the regular season suggests there is more work to be done to make the rule more practical and effective.

Although the NFL didn't overtly target CTE during its offseason work, its top medical officials say the new rules can only help.

"Specifically to CTE," Miller said, "we invest in research and research takes time to understand. The NFL wants to encourage an understanding of CTE and all the kinds of questions around it. So we will continue to put money against that. In the meantime, reducing head impact for the purposes of putting the head out of the game increasingly as a matter of prevention, is the best investment we can make, period."

Crandall's work will continue as well. Among other ongoing projects, Crandall said he is compiling a ranking of potentially correctable player behaviors that contribute to injuries. Lowering the helmet is atop the list. He declined to name the others but said some are unrelated to brain injuries. Regardless, those who participate in and observe the NFL can expect a continued effort to employ his data and research every offseason.

"There has always been significant discussion between medical people and the competition committee as it relates to injury rates or trends," said the NFL's Miller. "What's different now is that the level of information being brought to the competition committee is more significant.

"We can quantify [risky player behavior] with actual numbers. That's largely the result of engineering data and analysis only available to us in the past few years, and significantly invested in by the owners and the NFLPA. That's going to continue on an ongoing basis."