Injuries are an unfortunate part of football and something every team has to deal with, however, each team has differing injury rates. For example, as a Chargers fan my pre-season hopes drop every year to an injury that a star player suffers in training camp/OTAs (Derwin James, Russell Okung, Joey Bosa, Hunter Henry). I have learned to get past that, but also tried to find where the Chargers ranked in terms of games lost due to injuries.
That’s where Adjusted Games Lost comes in. Adjusted Games Lost (AGL), is a metric developed by Football Outsiders that takes information from a team’s injury reports, and uses it to create a number that can be compared to teams across the league. How does it work?
If a starting player is listed as out, or put on IR, then they contribute 1 full AGL to the team’s seasonal AGL score. If a player is listed as questionable on the team’s injury report, they contribute to approximately 27% of the team’s AGL that week. They use 27% because they found that 27% of the starters for a team that are listed as questionable on their team’s injury reports don’t end up playing. This metric obviously weighs starters more than reserve players based on how much they play, and their importance to the team.
There is an obvious correlation between wins and AGL as more injuries do lead to less games won. This does confirm priors as we saw the 49ers struggle to stay competitive this year after losing a lot of their team to injury.
In 2020, the Bucs were the least injured team when it came to AGL. To quote Tej Seth, “Don’t let Brady find this or else he’s going to take credit for the TB12 method leading to the Bucs having the least injuries this past season”. It is pretty crazy that Brady left the Patriots and went to the team that suffered the least amount of injuries in 2020. However, when looking at the AGL data in 2019, there was something interesting. The Bucs ranked 2nd in AGL in 2019. I previously thought injuries were random and unpredictable but there seemed to be slight stability year-to-year:
When looking at a sample from 2010-2020, it showed that injuries are slightly predictive from year N to year N + 1. There are a couple reasons why this could be the case. In the NFL, some teams do a better job of treating injuries and helping players recover than others. You also have teams like the Chargers who accidentally stab their starting QB’s lung 15 minutes before the game and injure them for three weeks. A good medical staff can help players to heal quicker from soft tissue injuries to places like the hamstring, quadriceps, biceps, and achilles. However, it is tough for medical staffs to prevent bone breaks/fractures as those are freak injuries and can be hard to predict.
Another reason why this can be stable from year-to-year is the use of young players on team rosters. Older players tend to break down more during the season and suffer more injuries in general than players with less wear and tear. Football Outsiders also found that the average year-to-year correlation for a team’s Snap Weighted Age is 0.59 meaning old teams stay old.
However, while it may seem like older teams would be more prone to injuries and would have a high AGL at the end of the season, that doesn’t appear to be the case. After looking at AGL and SWA together, there doesn’t appear to be any relationship between the two variables. This provides some evidence that AGL appears to be more indicative of a team’s medical/training staff, rather than the age of their roster. Even a team like the the 2019 Patriots who had a SWA of 28.6 had an AGL of 85.0 which is just slightly above average.
Now let’s take a look at some of the most and least injured teams of the decade when it comes to AGL
During the Andrew Luck era, the Colts were consistently one of the most injured teams in the league. Right when Luck retired in 2019, they became average. The stretch from 2010-2014 was the most brutal injury stretch of any team in the data.
Washington has had a bad string of injury luck. Most of it honestly can be attributed to the QBs. From RG3, to Alex Smith, to Colt McCoy, it seems every QB they’ve rolled out (aside from Kirk Cousins) has gotten hurt at some point. They’ve finished in the bottom 5 in multiple years at the QB position alone. In the analytics community, we are all pulling for Fitzmagic to stay healthy and finally get a full season with a good team.
Like I mentioned before, it seems that the Chargers are one of the most injured teams every year. And it’s ironic because their long-time starter in Philip Rivers never missed a start since he became the starting QB in 2006. They have had multiple medical team issues as well. In 2013, their long-time team doctor David Chao, aka Pro Football Doc left the team due to family issues, but he was facing backlash from fans and reporters about supposed malpractice. In 2020, I mentioned above what happened to Tyrod Taylor and his punctured lung. The Chargers recently hired a new Director of Sports Performance in Anthony Lomando, so it seems as if they might be turning a corner, and hopefully can keep their very talented roster healthy.
Now let’s look at some of the most healthy teams of the past decade.
The Titans are one of the teams that have enjoyed good injury luck and have been one of the healthiest teams of the past decade. Their lowest ranking was in 2014, where they ranked 22nd in AGL. However, despite having a relatively healthy roster, they never found any real postseason success until 2019, where they almost made the Super Bowl after sneaking in as a Wild Card. Before Tannehill, the Titans were stuck with mediocre QB play for many years. And having good QB play is essential to a team’s success, no matter how many times Derrick Henry touches the ball. Another interesting thing is the Titans have spent 2 first rounders in the past 3 years on players with “major” injury concerns entering the draft. Jeffery Simmons was a top 5 prospect in 2019 before he tore his ACL, and many people thought Caleb Farley was CB1 in 2021 before his back issues started to pop up. The Titans could be expressing their faith in their medical staff that they can keep these players healthy by drafting them in the first round.
The Rams are another team that has done extremely well staying healthy. They have been one of the top teams almost every year in terms of AGL ever since they finished last in 2011. In fact, since they moved to LA in 2016, they have finished 1st twice, 2nd, and 4th. There must be some secret in the water the training staff gives the players to drink in LA just like “Mike’s Secret Stuff” from Space Jam. The Sports Medicine & Performance staff led by Reggie Scott, Tyler Williams, and John Lovett have been amazing in keeping their players healthy. Now that they have Matthew Stafford, they have a legitimate shot to win the Super Bowl, and given that injuries are slightly stable from year-to-year, we can expect the Rams to be relatively healthy for 2021.
The final case I took a look at was not a team that was very healthy or very injured: the Philadelphia Eagles
The Eagles were very healthy over the first half of the decade, but this didn’t stay constant for the latter half. Interestingly enough, when Chip Kelly was hired in 2013, he also hired a Sports Science coordinator which was a completely new staff position at the time. The coordinator was Shaun Huls, and his story is very interesting because he was formerly a Navy SEAL before joining the Eagles. Kelly said he hired him because when he was the Head Coach at Oregon, “He employed a lot of the same conditioning techniques that he had learned about from studying the way the Navy SEALs train.” When Huls and Kelly were on the staff together from 2013-2015, the Eagles were among the league’s healthiest teams. The year after Kelly got fired, the Eagles were still very healthy, but suffered some brutal injury luck following 2016 while Huls was still on the staff. Doug Pederson may not have been as open to the introduction of Sports Science as Kelly was. Another cause could be that the Eagles had the 3rd highest Snap Weighted Age in 2018, and the 2nd highest in 2019.
To wrap it up, injuries are something that every team has to go through, but some have managed them better than others for the past decade. We can see that they are slightly predictive from year to year, and it is most likely a knock on how good or bad the training/medical staff is for each team. Some injuries are unpredictable and can’t be prevented such as ACL tears or bone fractures. But training staffs play a huge part in helping athletes recover from injuries that can linger such as soft tissue injuries. The next step teams can take is incorporating Sports Science to lessen the risk of their players suffering injuries.
Follow us on Twitter at @mfbanalytics! and myself @arjunmenon100
Are the Ravens just not on the graph labelled “How Injuries Affected Wins, 2020” ?
They’re hidden behind the Titans if you look behind the Titans logo
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