By Danny Blumenthal
AP PHOTO/REED HOFFMANN
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Saquon Barkley. Dak Prescott. Christian McCaffrey. Consider all the stars who missed significant time in 2020, and that this year’s all-injured team would be a strong Super Bowl contender. But just how widespread was the injury bug this year? Was the rate of injuries actually higher or did it just seem that way because of the big names missing from the action? Well, according to nflfastR play-by-play data, this season was truly a brutal one on the injury front, seeing about a 14% increase in 2020 over the average rate from the previous decade.
Using nflfastR play-by-play data for every game since 2010 and filtering to only include plays which featured the word “injured,” I ran a t-test (a method for determining whether a significant difference exists between averages) to see whether the injury rate was significantly higher in 2020 compared to the decade before (see below).
Clearly, there was a significant increase in the injury rate, which climbed from just under 1.5 injuries per 100 plays to 1.73 injuries per 100 plays. This may not seem like a major difference, but taken across an entire season, the extra injuries accumulate quickly. In fact, given that at least 45,000 plays are run each season, there have been more than 100 additional injuries this year than would be expected at the previous injury rate.
Prior to 2020, the most in-game injuries in a season had occurred in 2015, when 786 play stoppages were reported for injuries. That year, the NFL introduced impartial concussion spotters, who could stop play if they believed a player had suffered a head injury. This new emphasis on tracking concussions also led to more players self-reporting head injuries to team doctors, further increasing the count. In the end, reported concussions rose more than 30% compared to 2014, pushing the number of reported injuries higher than ever before.
Still, the rise in concussion awareness does not tell the whole story for 2015. Numerous stars, such as Jamaal Charles, Jordy Nelson and Joe Flacco, lost much of their seasons to torn ACLs. Other lower-body injuries, such as torn MCLs, rose more than 20% that year as well, with Peyton Manning, Dez Bryant and Le’Veon Bell among those who missed time. And yet 2020 eclipsed the 2015 high-water mark for injuries, with more than 800 injuries recorded.
Many analysts projected that injuries might spike in 2020 as a result of the COVID-19 pandemic. Given the lack of organized team activities (OTAs) or minicamps before the season and no preseason games, it was thought that players could not prepare themselves properly. Instead of gradually working their way up to full intensity like in a normal season, they would jump right in for Week 1 without letting their bodies adapt. As a result, many thought that the start of the season would see a rash of injuries.
While more players were hurt in 2020 compared to previous years, a dive into the data, breaking down the results by week, reveals the evidence does not clearly support those predictions.
If the only influence on injury rates was preparation time, you would expect the difference between the blue line (2020) and the red line (2010-2019) to be highest in the initial weeks of the season. However, this does not appear to be the case. In fact, Week 1 of 2020 was actually one of two weeks that saw fewer injuries than average.
Instead, a look at the week-to-week injury rates saw greater disparity as the season wore on. Numerous San Francisco 49ers (such as quarterback Jimmy Garoppolo and star defensive end Nick Bosa) were knocked out in Week 2; Miles Sanders and Zach Ertz were victims of the injury bug in Philadelphia in Week 6; and standout defenders Stephon Gilmore and Quinnen Williams saw their seasons end in Week 15. Week 7 was especially brutal, taking Odell Beckham Jr. (torn ACL), Chris Carson (foot sprain) and Andy Dalton (concussion from a dirty hit) out of commission. As the following table shows, it saw the second-most injuries of any week in the past decade.
Overall, four of the 10 worst weeks for injuries occurred in 2020: Weeks 7, 11, 14 and 15. Again, this pushes back on the “no-preparation” theory, as players likely should have been in a routine by this point. In addition, Week 1 (when injuries would be expected to be quite high) actually was 169th in overall injury rate, out of the 187 weeks since 2010. Just like how there weren’t actually more injuries in the wake of the 2011 NFL lockout, it appears as though the reduced offseason may not have affected injury rates.
So, if the “no-preparation” theory is bunk, what then might account for the rash of injuries this year?
One potential explanation is the rising prevalence of turf fields. Researchers from Georgetown University have found that knee injuries are significantly more common on artificial turf than on grass, and the NFL Players Association has argued that non-contact injuries are 25% more common on turf.
Fifteen out of 32 teams played on turf in 2020, the highest rate in at least a decade. Prior to the season, the Los Angeles Rams and Chargers abandoned their grass-field homes for the turf at SoFi Stadium, and the New York Jets and Giants changed the turf in MetLife Stadium. The field at the latter is widely thought to have contributed to the 49ers’ injuries in Week 2. Coach Kyle Shanahan reported that players found the field “sticky” when playing at MetLife. If players couldn’t get their feet out from under them when making cuts, it may make sense why Nick Bosa and Solomon Thomas both tore their ACLs that day.
Another potential explanation is a shift in playing style. Running plays were called a little more than 3% more in 2020 than in 2019, reversing a trend of decreasing rushing attempts from the past few decades. When teams pass, they spread the field out, reducing the number of collisions. On the flip side, when teams run the ball, players all crash together. Therefore, it should come as no surprise that running plays result in significantly more injuries than passing plays. While this may not be the primary cause of the rise in injuries, it could play a role.
A couple of other theories for the rise in injuries are, however, COVID-related. Team medical staffs and trainers face growing responsibilities in the era of COVID-19. Every team has assigned an “infection control officer” (usually the head athletic trainer). In addition to their usual roles in treating players’ injuries, these officers are now also in charge of educating players about health and safety protocols, sanitizing equipment and even contact tracing for the team. Since they need to review practice footage and interview potential contacts, this process can be a massive undertaking, cutting into their normal duties and reducing the amount of time they can devote to preventing football-related injuries.
Similarly, since they are exposed to so many people, trainers are often at higher risk of being infected themselves. This year, the trainers from the Kansas City Chiefs, Minnesota Vikings, Baltimore Ravens and Tennessee Titans all tested positive. If a team’s top trainer is out, less experienced staff members must replace them. Finally, players who go onto the reserve/COVID-19 list during the season can’t practice with their teams. As a result, it may be tough for them to renew their routine, and they may suffer from the same increased injury rate hypothesized by analysts prior to the season.
Nevertheless, this year’s injury bug may just be an anomaly. Many injuries were “fluky,” such as Beckham leaping into a teammate and tearing his ACL, and these are unlikely to be repeated in 2021. In addition, while teams ran the ball more often in 2020, this reversed a historical trend of increased passing. If teams learn from the best offenses, such as Kansas City and Buffalo, and pass the ball more often, then this year could be a one-off. On the flip side, the ever-increasing number of turf fields could lead to more injuries if these fields are not properly inspected.
Overall, to determine if 2020 was an anomaly or if this is the start of a scary injury trend, we would suggest looking at a couple of variables going forward. First, what types of injuries are occurring? Soft-tissue injuries are thought to be more easily prevented than others, so if there is a high rate of soft-tissue injuries after a full offseason in 2021, then that would be troubling. In addition, look out for the rate of passing vs. rushing plays. If teams are passing more in the first few weeks of the season, it could be a good sign for the NFL on the injury front.
Editor’s Note: If you have questions about this article, please feel free to reach
out to Danny at harvardsportsanalysis@gmail.com.
Thank you for reading!
