Examining Adjusted Games Lost can help explain the NFC North in 2018

A cliché among sports fans is that injuries are not an excuse for losing, but in truth, injuries are in fact a very good excuse. In fact, having your good players unavailable and replacing them with worse players makes a team noticeably worse, and almost nothing correlates better with winning than injury rate.

Of course, not all injuries are created equally. If your backup running back is injured, it really doesn’t matter. If your starting quarterback is hurt, it matters a great deal. Every year, Football Outsiders publishes Adjusted Games Lost (AGL), which attempts to account both for the quality of injured players as well as for players who may be playing while hurt.

And it works pretty well. When the Green Bay Packers went 12-4 in 2014, they were the third-healthiest team in the league. When they went 8-7-1 the previous season, they ranked 30th. Aaron Rodgers was obviously a big part of that 2013 season, but that’s what AGL is designed to catch.

It will no doubt interest you to know that the Chicago Bears were the third-healthiest team by AGL last season, which greatly contributed to their success in 2018. The Packers were, for the second consecutive season, 21st, which went a long way to undermining their efforts. The Bears’ health was a huge improvement over four consecutive seasons of ranking no higher than 27th. That’s a big jump, and while some regression is likely for Chicago, injury luck isn’t totally random. In fact, one of the biggest predictors of future injuries is previous injuries. In 2019, the most likely outcome is the Packers landing around 21st again, and the Bears falling to something like 10th.

In the AGL era (going back to 2010) the Packers are one of the most injured teams in football, with an average of 78 AGL per season, 7th-worst since their Super Bowl season. (Big thanks to APC’s Jon Meerdink for compiling historical data.) The team had a small spat of health in 2014 (3rd) and 2015 (9th), but they’ve collapsed back into the lower third of the league more recently, and their results have reflected that.

Research by Football Outsiders also shows that wide receivers, tight ends, offensive lineman, and especially defensive backs have seen a spike in injuries lately, and you can see it in the Packers. Their secondary has been a virtual hospital ward, and both Jordy Nelson and Randall Cobb were consistently missing time or playing hurt over the past three seasons. Geronimo Allison’s injury last season did as much to hurt the Packer passing attack as anything else.

Corners in particular are both extremely important to a team’s overall health and extremely injury prone, and if you don’t have too many, you don’t have enough. To the extent that the Packers have struggled in the Rodgers era, it’s DB health that has played an extraordinarily large role, and while recent drafts focusing on the position have varied widely in terms of success, the approach is a smart one. The good news is that, at least on defense, the Packers have stocked the secondary with high draft picks and pure athletes. While their depth is admittedly raw and Kevin King is a dicey proposition, they are in much better shape than the days where Ladarius Gunter was forced to match up with Julio Jones in a playoff game. If your team is likely to suffer injuries, you need depth where it counts.

The defending NFC North champion Bears also have some depth issues. Even if they don’t experience a huge decline in injury luck, if any member of their front four should get hurt, they will have a huge drop-off to their backups. The Bears have traded away a lot of draft picks, and while they’ve turned many of those picks into legit stars like Mack, it has had a negative impact on their depth. The Packers have their vulnerabilities, especially in the receiving corps, but they actually have decent defensive depth at this point. The Bears will likely be more injured than they were in 2018, and that may open the door just enough for a challenger.