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2015 Cowboys Defense: Three Stats That Will Leave You Scratching Your Head

The stats say the lack of takeaways and the inability to get off the field are killing the Cowboys defense, but there may be more to it than that.

Andrew Redington/Getty Images

You may find this hard to believe, but just two weeks ago, the league announced that Sean Lee had been named NFC Defensive Player of the Week on a Cowboys team that stood at 2-0 at the time.

It seems like ages ago, but at the time, the Cowboys boasted the league’s top-ranked run defense (53 yards per game) and were third in overall defense (257.5 yards per game). Two games later, the run defense has dropped to ninth overall (92 yards per game), courtesy of the Atlanta Falcons, who gashed the Cowboys for 158 rushing yards. And in terms of overall defense, the Cowboys have tumbled to 14th overall, allowing 348 yards per game.

But does all of that mean the defense is bad? Sure, the defense wasn't able to get any stops late in the last two games, stops that perhaps could have won both games. And while they are not a league-leading unit by any means, do yards allowed or points allowed (19th) really tell the whole story of the defense?

If you think they do, then you're probably better off looking for some other reading material, because this post is not going to be to your liking.

We know that Rod Marinelli measures the performance of his defense with two sets of stats, turnovers and the Aikman Efficiency Ratings.

Stat # 1: Takeaways

The turnover story is fairly simple. Last year, the Cowboys had the second most takeaways in the league with 31. But that magic elixir dried up faster than you can say regression to the mean, and the Cowboys have just three takeaways in four games so far this year, tied with seven other teams and ranked a joint 24th in the league. Ironically, last year's leaders in takeaways, the Texans (34 takeaways in 2014), are ranked last with just two interceptions in four games. Also noteworthy: There are 14 teams with four takeaways or less through Week 4. Not one of them has a winning record and nine have a losing record.

If you're looking for a reason why the Cowboys are where they are, you don't need to look much further than the -3 turnover ratio. But if you'd like to dig a little deeper, the Aikman Ratings offer some additional perspective on the defensive performance.

Stat # 2: Aikman Efficiency Rating

The Aikman Ratings are one of the stats most closely correlated to wins in the NFL. In fact, outside of scoring differential, no other stat correlated more closely to wins in 2014. The Rating combines seven stats in five categories to provide a picture of offensive and/or defensive strength.

The exact formula used to arrive at the ratings was never made public, but we do know what the seven stats are and how they are weighted in the formula. Let's walk through the individual metrics for the Cowboys defense after four weeks.

Adjusted Points (Points allowed minus points on returns and safeties): Over four games, the Cowboys allowed 101 points. Seven points came from a fumble returned for a TD by the Giants. The 92 remaining points rank the Cowboys 19th overall with 23.5 adjusted points allowed per game.

Turnovers: The Cowboys have three takeaways so far, which ranks them a joint 24th in the league.

Red Zone Efficiency. The Cowboys opponents have had 15 red zone possessions. At seven points per possession, opponents could have scored 105 points, but only scored 71 for an efficiency percentage of 68%, the 14h best value in the league.

Yards per play: The Cowboys are allowing 3.7 yards per attempt on the ground (6th) and 7.1 yards per attempt through the air (9th).

First down achievement/Third down defense. The Cowboys have allowed an average of 22 first downs per game, which ranks them 22nd in the league. The Cowboys' third down percentage is even less impressive, their 44.2% conversion rate allowed ranks them 27th in the league.

The following table summarizes all the data above, with a color code added that shows a top ten performance in green, an average performance in yellow and a bottom 10 performance in red.

Metric Weight League Rank per Week 4, 2015
Adjusted points 20% 19th
Turnovers 20% 24th
Red zone efficiency 20% 14th
Yards per rush attempt 10% 6th
Yards per pass attempt 10% 9th
First downs allowed 10%
3rd down conversion percentage 10% 27th

The table tells a fairly straightforward story. The Cowboys defense is a surprisingly solid unit in terms of gains allowed. On a per play basis, they are a top ten unit against the run and against the pass. But they can't get the opposing offense off the field, at least not with any kind of regularity. They are hardly getting any turnovers, and they have a hard time stopping opposing teams on third down. They do stiffen up a little in the red zone, but their inability to get off the field ultimately is the undoing of the unit and the reason why they've given up as many points as they have.

Stat # 3: 4th Quarter Performance

But there's another issue that doesn't show up in these stats. Here's a look at the points allowed by quarter so far this year.

Cowboys points allowed by quarter through Week 4, 2015
Quarter 1st 2nd 3rd 4th + OT Total
Points allowed
17 20 17 47 101
NFL rank 17th 10th 14th 31st 20th

Over four games, the Cowboys have allowed 54 points in the first three quarters, and 47 points in the fourth quarter and overtime. Only the Giants (50 points) have allowed more points late in the game. Think about that. ALMOST HALF of all points allowed were scored on the Cowboys in the 4th quarter or OT.

When Jason Garrett was asked a few years back which stats the Cowboys pay the most attention to, he answered turnover differential and 'winning the fourth quarter,' because he believes they are the two stats most significantly correlated with winning in the NFL. Given the stats we just looked at, Garrett can't be particularly happy.

Despite all the injuries they have to deal with, the Cowboys have been in all four games until well into the fourth quarter. They pulled out two wins against the Giants and Eagles, and lost two against the Falcons and Saints. And when you think back to each game, the difference between winning and losing usually came down to one or two plays the Cowboys made or didn't make.

The Cowboys don't have a top defense. But that defense will look a lot better with a few more takeaways under their belt. And if they can improve their third down performance, they may even become a good defense. And that may be enough.

Because you don't need a top ten defense to win the fourth quarter. And you won't need a record-breaking offense to win the fourth quarter either. You will need better execution and probably also better play calling to win the fourth quarter. But most of all, you'll need fresh bodies. And right now, that may be the biggest challenge the Cowboys face.


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