The Impact of ACL Surgery on Fantasy Performance: Running Backs

ACL injuries are one of the most common injuries in the NFL, specifically for skill position players. That problem unfortunately is not going away any time soon as football is one of the sports with the highest rates of ACL injuries, regardless of position, due to the physical demands of the sport. According to the 2021 NFL Health and Safety data, there were 71 ACL injuries in the league last season when you combine the Preseason and Regular season, which is 20 more than the previous year. There’s no doubt – surgical approaches and rehab techniques are improving as the years go by, but one thing is for sure – ACL injuries in the NFL are here to stay.

Of course, there are outliers like Adrian Peterson in 2012, who won the MVP after tearing his ACL the year prior. The average return to play timeline according to the vast majority of research is about 9-12 months, but the tricky thing is that return to play does not always equal return to performance. In other words, just because an athlete is back on the field does not mean he will produce at the same level he did before the injury. Some athletes struggle with quadriceps strength and hypertrophy (size), knee range of motion, stiffness, swelling, etc. for months after their surgery. Of course, one aspect that’s extremely difficult to measure is an athlete’s psychological readiness to return to sports, or in other words, their confidence in their own knee after a traumatic injury.

When an NFL player tears his ACL, it immediately ends his season and potentially compromises the following one…or even his career. I often go on other podcasts or get asked questions with a lot of people assuming something along the lines of “ACL injuries aren’t that big of a deal anymore” or “Players are recovering way faster than they used to, so ACLs aren’t as bad as they used to be.” While there’s some merit to this that the best athletes in the world are recovering better than they were a decade ago, is the general public right in assuming that ACL injuries aren’t as big of a deal as they used to be?

With this study, I wanted to quantify the effect of ACL injuries on the performance of running backs from an efficiency standpoint and a fantasy performance standpoint. I’ll outline my methods in the following sections and then give some key takeaways and conclusions about how to use this data in the future. Next week, look for a similar research article on the wide receiver position.

As I usually reference when talking about injuries, the recovery process is non-binary and there’s a lot of nuance to understanding how injuries impact a fantasy season. If you’re interested in discussing these topics more or have questions, be sure to find me on Twitter or message me in our Discord server. You can also find more of my injury analysis in the 2022 Ultimate Draft Kit.

Methods

For this study, I chose to include running backs with an ACL injury from the years 2015-2021. I wanted to do this for two reasons. First, I wanted to capture more of the “modern” medicine and rehab approaches and avoid including players who were playing in the league 10+ years ago as times are obviously changing. Second, for NFL injury reporting, it’s much more difficult to find details on player injuries the further back we go in league history. With that said, I do want to just take one second to acknowledge Adrian Peterson‘s insane 2012 MVP season the year following his ACL injury and give a shoutout to Jamaal Charles, who tore his ACL for the first time in 2011 and then came back in 2012 and totaled over 1,700 yards from scrimmage. These two players are perfect examples – elite backs are capable of returning from this injury in year one, but the data below shows they could be outliers. More on that soon…

Continuing with the methodology behind the study, I did not control in this sample backs who had multi-ligament and/or meniscus injuries on top of their ACL injuries, as I feared that would make the sample far too small. However, it is worth noting that in the rehab world, we have to progress these athletes slowly compared to “clean” ACL injuries. Intuitively, fantasy managers will want to factor that analysis into their takes of players coming off the surgery for future reference.

The final thing to point out here is that I really tried to focus on only including fantasy-relevant names in order to further tailor the study to what we as fantasy players care about – how these players perform for fantasy after they’re back on the field. There were more players who met my criteria that I did not include in the study given that they were 2nd or 3rd string players who were never on our fantasy radar anyway. Including them in the study would have likely made the data and outcomes look worse.

As you’ll see in the charts and graphs below, I split this study into two different parts:

1. How NFL RBs perform in year one after the surgery compared to year two
2. How NFL RBs perform in year one relative to their career averages before the injury. In other words, if a player tore their ACL in 2018 but entered the league in 2015, I used averages from 2015-2018, excluding the game in which the player was injured.

Metrics Utilized

When looking at how to quantify a player’s performance after injury, I could have used any number of data points, but I chose to focus on efficiency metrics rather than raw numbers. Why? In these types of studies, it’s extremely difficult to quantify so many other factors that affect fantasy performance – coaching scheme, offensive line play, QB play, etc. etc. By looking at efficiency metrics that are (mostly) agnostic of their teammates, I felt that it was a better representation of the individual’s performance. Of course, we as fantasy players know football is a team game and my prior sentence is almost never true, but you know what I mean.

Below is a list of metrics utilized with a short definition for each efficiency metric as well as the source of the information in parentheses:

• YPC = Yards per carry (The Fantasy Footballers Player Profiles)
• YCO/A = Yards after contact per attempt (PFF)
• Y/T = Yards per touch (Pro Football Reference)
• Elusive Rating = (Missed Tackles Forced) / (Designed Run Attempts + Receptions) * (Yards After Contact Per Attempt * 100); A PFF signature stat
• Fantasy PPG = Fantasy points per game (The Fantasy Footballers Player Profiles)

Comparing Year 1 vs. Year 2 After ACL Surgery

So this information is of course a lot to digest. Let’s take a second to orient to the information in the charts above. On the X-axis, you’ll find efficiency metrics such as fantasy points per game (FFPG), yards after contact per attempt (YCO/A), Yards per touch, and YPC (yards per carry). On the Y-axis, is the raw score for each of these metrics. The green bar represents year one after ACL surgery, while the grey bar represents the 2nd season removed from surgery. For example, Dalvin Cook tore his ACL in 2017, so his green bar represents his metrics from 2018, and the grey bar represents his metrics from 2019.

Discussion Points

• Excluding players who retired after their ACL injury, the vast majority of players were more efficient in yards per attempt, yards per touch, and fantasy points per game in the second year following ACL surgery.
• Age does seem to matter. Younger backs in this sample (younger than 26) were more likely than veteran backs to have a bounce-back season in year two after ACL surgery, at least when you look at efficiency metrics and fantasy points per game. Unfortunately, late career ACL injuries have the potential to be career-threatening (Darren Sproles, Lamar Miller, etc.)
• I was really hoping to have a much bigger sample to draw from here, but the reality is that fantasy football managers should use this data for younger players. To illustrate this, take a look at Rashaad Penny, Dion Lewis and Dalvin Cook‘s data above. Not only do we know younger athletes heal more reliably than veterans at the back of their career, but these athletic players struggled in year one then had a boom in production and efficiency in year two.

Comparing Performance in Year 1 vs. Pre-Injury Levels

Again, just like in the first table above, we’re looking at the same metrics on the X and Y-axis. The primary difference here is that we’re now looking at comparing player performance Pre-injury to the player’s first season back on the field after surgery. For example, Saquon Barkley tore his ACL in 2020, so the green bar above is looking at his career averages from when he entered the NFL to the time in which his injury occurred. The grey bar is 2021, his first season on the field after his surgery.

Discussion Points

• This is really where the value of this article lies, in my opinion. Across the board, we see that the grey bar is lower than the green bar for almost all of the efficiency metrics and fantasy points per game. As we just discussed, this means that in year one following surgery, players are generally less efficient and put up fewer fantasy points per game in their first season back.
• Another thing to point out again is that some players see not just a small decline in efficiency, but a relatively large decline in efficiency.

Conclusion & Takeaways

There’s no doubt that players can return to an elite level following an ACL surgery. After all, we’ve seen some elite production from Dalvin Cook in recent years, Todd Gurley had an incredible few years once healthy, and we’ve seen backs in the past like AP and Jamaal Charles be successful. But, there’s an edge to gain in fantasy football with this population of players returning from ACL surgery, especially running backs in year one off the surgery.

There will no doubt be outliers over the next few seasons, and the medical field will continue to develop better surgical and rehab techniques as the years go by. But, as it stands right now, the data shows that RBs coming off an ACL surgery tend to be less efficient and have worse fantasy seasons in their first year following surgery when compared to their pre-injury career averages and when compared to year two after surgery.

Moving forward, fantasy managers should understand that it’s more likely than not when selecting a player after their ACL surgery, they’re less likely to put up numbers that they were in previous seasons, and as a result, avoiding these players, or taking them only when they fall past ADP, can be of tremendous benefit. Furthermore, this data helps to point out that while it might be smart to fade backs coming off this surgery in year one, there could be a very solid “buy low” window for players coming off the injury in year two, especially if those players are young, athletic and have excellent draft capital.

This study certainly has its limitations and ignoring to acknowledge that would be of disservice to the reader. First, this data does not factor in when an athlete had their surgery or their injury. For example, a back who had an ACL injury in Week 17 is less likely to return to form than an RB who got injured in the first week of training camp 4 months earlier. This data did not factor that in. Second, this study didn’t have as many players in it as I would have liked. But again, by only trying to include the fantasy-relevant names (at that time), it helps to capture the player types that we as fantasy managers care about. In other words, the data on 2nd and 3rd string backs might not be all that helpful and could skew the data one way or the other, so I did not include those player types.

For 2022, the key considerations here are for names like J.K. Dobbins and Gus Edwards, two backs who are entering year one following surgery. If the data above carries any weight, it’s unlikely these two guys are producing at their pre-injury levels in 2022, especially early in the year. In addition, this data provides some encouraging perspective on Saquon Barkley as he enters year two after surgery.