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Will 2015 Dallas Cowboys Defense Be Better Due To Improved Health?

Will the Cowboys be a healthier team in 2015, and what would that mean for the 2015 season?

Tim Heitman-USA TODAY Sports

The big news on the health front for the Cowboys in 2014 was probably Tony Romo's struggle to to come back from back surgery. Tony Romo dominated the headlines all season with his limited practice participation, the fractures to the transfer process in his back, and other injuries that kept him on the injury report for all 18 games, though he only missed one. The only other notable injury on offense was Doug Free, who fractured his foot in Week 6 against Seattle and missed three games, then re-injured his ankle against the Eagles in Week 14 and missed the final two regular season games.

The defense was an entirely different picture. The year started out badly when Sean Lee was lost for the season with a torn ACL in OTAs, and it didn't get any better when Devonte Holloman suffered a career-ending spinal injury, and rookie DeMarcus Lawrence fractured his foot - all before the season started. Here's a look at the games missed by key players on defense last year:

Sean Lee: 16
Morris Claiborne: 12
Justin Durant: 10
DeMarcus Lawrence: 9
Jack Crawford: 9
Anthony Spencer: 3
Rolando McClain: 3
Bruce Carter: 3
Terrell McClain: 3
Tyrone Crawford: 1

At the end of the day, injuries are part of the game in the NFL. Every team is affected by injuries at some point in the season, and often it's a team's ability to compensate for those injuries that makes the difference over the course of a season. But how do the Cowboys injury totals compare with other teams?

Every year, Football Outsiders publish their statistical study of team health from the previous NFL season, and today we'll take a look at where the Cowboys rank on their list. First, a little background on FO's Adjusted Games Lost (AGL) stat. In their own words:

... the key ideas underlying AGL are that all players don't affect winning and losing equally, and missing a game isn't the only way a player injury affects winning and losing. Injuries to starters, important situational reserves (e.g., nickel cornerbacks), and injury replacements (i.e., new permanent starters) count towards AGL, whereas injuries to benchwarmers don't. Similarly, injuries that land a player on injured reserve affect AGL more than injuries that force a player to be listed as "questionable," which in turn affect AGL more than injuries that lead to a "probable" game status.

By FO's definition, the Cowboys finished the 2014 season with 76.1 Adjusted Games Lost, which ranks the Cowboys 19th in the league, meaning they suffered slightly more AGL than the average NFL team. The following table shows the Cowboys' injury stats over the last seven years compared to the league average.

Adjusted Games Lost to Injury, 2007-2014
Team 2007 2008 2009 2010 2011 2012 2013 2014
Cowboys 45.8 53.3 22.5 31.8 62.5 86.5 67.9 76.1
NFL Average 45.0 52.7 53.9 50.9 60.0 64.5 67.6 74.3

One important thing to note is that the AGL average is increasing year after year. Scott Kacsmar of Football Outsiders writes that this may have to do with teams doing a better job of reporting injuries, and also argues that  FO now "have better information to identify reserves who play a significant amount of snaps on a consistent basis and therefore should count in AGL."

But what's important for Cowboys fans to understand is that only once in the last eight years have the Cowboys had an injury rate that was significantly above average. Let that sink in for a minute. For all the wailing and gnashing of teeth about the Cowboys injury situation, 2012 was the only recent year in which the Cowboys suffered from an unusually high injury rate.

The reason why many fans feel the Cowboys have been hit harder by injuries than the average team is that you tend to notice injuries more when they are not evenly distributed. And this is especially true for the 2014 Cowboys.

The 2014 offense, despite the constant headlines about Tony Romo's health situation, ranked as the second-healthiest offense in the league with an AGL of just 9.3.

The 2014 Cowboys defense on the other hand had the fifth-highest injury rate in the league with 66.8 Adjusted Games Lost. Of that total, 23.0 AGL were on the defensive line (3rd highest), and 31.7 were at linebacker, the highest value in the league last year.


Statistically speaking, there's reason for optimism and reason for pessimism in these numbers - and that reason is called "Regression to the mean." This statistical phenomenon describes the fact that if a variable is extreme on its first measurement, it will tend to be closer to the average on a second measurement. In our case today, it means that teams with a very high injury rate tend to have a better injury situation in the following year, while teams with an extremely low injury rate tend to have more injuries the following year.

Specifically, there's a good chance the Cowboys defense will see a lot less injuries in 2015. This is a good thing. Unfortunately, if you were counting on the offense to bail out the defense by maintaining its fifth-ranked scoring pace of 29.2 points per game into the new season, regression to the mean has some less favorable news for you: Given that the Cowboys offense was one of the healthiest units in the league last year, we have to expect that they'll see more injuries in 2015, and that might impact their ability to score. Then again, the Colts had the fourth-worst AGL on offense last year (56.6) and still managed to score 458 points, just nine points less than the Cowboys.

We know that injuries are a fact of life in the NFL. We also know that a good amount of injuries suffered are random: the healthiest team in 2014 (DEN: 36.9 AGL) had the 8th most injured team the year before; the second most healthy team in 2013 (KC: 40 AGL) was the 7th most injured team a year later (98.8 AGL). These types of swings happen every year, but they are the outliers. Most teams will oscillate to various degrees around the league average, like the Cowboys have done.

The Cowboys probably won't be significantly healthier (or unhealthier) in 2015 than they were in 2014. It can happen, but the odds of that happening are long. But there are three things the Cowboys can look forward to.

1. A better distribution of the injuries across the entire roster will make the impact of those injuries less crippling.

2. The team has gotten younger every year, and that youth will eventually pay off. As players become older, the risk of injury increases exponentially. The injury risk for younger players is much lower, and the performance upside much higher.

3. Over the last few years, the depth across the roster has improved significantly. And better depth will allow you to better compensate for the inevitable injuries.

Will it be enough? I don't know. What I do know is that despite all their injury woes, the Cowboys were a catch away from the NFC Championship game last year. And with a slightly better distribution of their injuries in 2015, they could go further than they did last year.

That may not be much in terms of consolation for those of us waiting with bated breath for that big FA signing on defense, but ultimately it will be the number and distribution of injuries that determine the Cowboys' 2015 fate, not the two or three FA additions that are still to come on defense.

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