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# Dallas Cowboys' Defensive Front Seven: Rob's Mob Was Probably Better Than You Thought

I know that the title of this post is already a little bit of a spoiler, but I'll ask you this anyway: Before reading on, make a mental note of where you think the Cowboys defensive front-seven ranked last year among all 32 NFL teams. Pick a number based on whatever real or imaginary stat you want. Got a number between 1 and 32? Good, now read on.

Dan Graziano, ESPN's NFC East blogger, called the defensive line the "Cowboys' hidden treasure" yesterday. Dan is basing this assessment on the expectation that we could see an improved pass rush from the defensive end position this year.

There was a time not so long ago when a defensive front seven's performance was measured by sacks and yards allowed. Using those two metrics, the Cowboys already ranked seventh in total sacks and also ranked seventh in rushing yards allowed last season. A year earlier the Cowboys ranked 16th and 12th respectively, so an argument could be made that Rob's Mob has already improved from an average unit in 2010 to a top ten unit in 2011.

Today, there are more statistics available to help evaluate a defense's performance at the line of scrimmage. After the break, we're going to use a number of advanced metrics to look at how the defensive front seven performed last season. You may be surprised by the results, but if you're a Cowboys fan, you'll probably like what you're about to see.

For this post, we'll be using some of the advanced metrics provided by our good friends at Football Outsiders to assess the defensive line performance - Line Yards, Power Success, Open Field Yards, Stuffs and Sack rate - to get a feel for where the Cowboys defensive front seven ranked last year.

Based on regression analysis, the Adjusted Line Yards (ALY) formula takes all running back carries and assigns responsibility to the offensive line based on the following percentages:

Losses: 120% value
0-4 Yards: 100% value
5-10 Yards: 50% value
11+ Yards: 0% value

These numbers are then adjusted based on down, distance, situation, opponent, and many other factors.

The defensive line stats (more accurately, defensive front seven stats) are derived from the performance of offensive lines against each defense, adjusted for the quality of offensive opponents.

Using Adjusted Line Yards, this is how the Cowboys performed in 2011, and how that compares to the previous year:

 Year Rank Adj. Line Yards RB Yards NFL Avg 2010 22 4.27 4.40 4.18 2011 10 3.92 4.03 4.31

The Cowboys ranked 10th in terms of adjusted line yards (ALY) last year. This means that the opposing offensive lines found it particularly hard to create a lot of push against the Cowboys in the run game. The 3.92 ALY average for the Cowboys is almost half a yard below the 4.31 league average (and is the lowest value the Cowboys have achieved since 2007). That in itself is pretty remarkable for a unit that ranked 22nd in this stat category in the year before, but perhaps even more surprising is that if you look at the full team rankings, the Cowboys rank higher than all three of their division rivals. The Eagles (16th), Giants (20th) and Redskins (22nd) all allowed opposing offensive lines to push them back further than what the Cowboys allowed.

Of course, the standard reply to the ALY metric is something along the lines of : "As long as a guy is a good pass rusher, I couldn’t care less whether he gives up 3.8 or 4.2 yards per attempt against the run. It’s a passing league, and getting to the QB is the name of the game. Perennial playoff contenders are built around passing the ball and rushing the passer."

This argument is not without merit, so let's take a detour and look at FO's pass rushing metric

The Cowboys had 42 sacks in sixteen games last season. Because other teams may have played more or less snaps than the Cowboys, what FO do with the raw sack count is they adjust the number of sacks for each defense for pass attempts, down, distance and opponent to get a number that's comparable across all teams. The Cowboys rank a very respectable sixth with an adjusted sack rate of 7.7%, up from 11th in 2010.

Note that the Cowboys are only ranked two spots behind the Eagles (4th) and ahead of the Redskins and Giants (9th and 10th) in this metric. The Cowboys were one of only four teams (MIN, HOU, DEN) to rank in the top ten in both adjusted line yards and adjusted sack rate.

Effectively, the Cowboys defense was good at both stopping the run and rushing the passer. Now back to the performance against the run.

Running Back Yards

The running back yards in the table above are the yards per carry by running backs against the Cowboys defense according to standard NFL numbers. The RB Yards allowed by the Cowboys defense are very close to the ALY, which means that the opposing running backs weren't able to get more yards than the (little) yardage generated by their offensive line.

The fact that both numbers are fairly low is indicative of not only a strong defensive line but also of linebackers and defensive backs who are willing and able to regularly make tackles against the run. And if you've watched Sean Lee flying around against the run and making tackles all over the field, you'll know exactly what I'm talking about. On the few occasions where a runner gets past the defensive line, the Dallas linebackers and defensive backs are good at pursuit and tackling.

A look across the East shows that the Eagles have the biggest gap between RB Yards and ALY (+0.50), an indication of a sub-par performance of their linebackers and defensive backs against the run.

Stuffed

The Cowboys defense stuffed the opposing runner at or behind the line of scrimmage on about every fifth run, or on 22% of all runs, which ranks the Cowboys 9th in the league.

Long runs

Football Outsiders differentiate between two types of long runs:

Second level yards: Percentage of rushing between 5 and 10 yards out from the line of scrimmage

Open field yards: Percentage of rushing yards more than 10 yards past the line of scrimmage

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In both categories, the Cowboys defense put up strong numbers. In this metric, the Cowboys are a borderline top ten unit both in terms of second level yards and in open field yards.

 Year Second level yards Second level rank Open field yards Open field rank 2010 1.10 14 0.87 19 2011 1.13 11 0.66 9

In both metrics, we can already begin to see the effect of the no-run-zone enforced by Sean Lee, who was smacking people to the ground with or without a cast. Add either Dan Connor or Bruce Carter to the mix, and the Cowboys should see a strong improvement in both metrics this season.

Power Success

Percentage of runs on third or fourth down, two yards or less to go, that achieved a first down or touchdown. Also includes runs on first-and-goal or second-and-goal from the two-yard line or closer.

Despite having largely the same personnel on the field as they did in 2010, especially along the defensive line, this is the area where the 2011 Cowboys showed the most improvement under Rob Ryan.

 Year Rank Power Success NFL AVG 2010 29 70% 61% 2011 10 57% 62%

Where the 2010 unit was ranked 29th, the 2011 unit moved up into the 10th spot in the league, losing just 57% of their short yardage stands on third or fourth down, or on the goal line. And if you appreciate line play, this may be the most telling stat of all, because when it's one-on-one on the goal line, there is little room for subterfuge, for unorthodox lineups or other surprises. This is where it's man against man, where brute strength and superior technique are the only things that count - and where Rob's Mob has to earn its name.

Summary

I don't know where you ranked the defensive front seven when you started reading this post, but chances are it was not in the top ten. Yet almost any way you look at it, the front seven ranked among the top ten units in the league. More importantly, 'Rob's Mob' improved from an average to a top ten unit last year.

Defensive end Marcus Spears recently said he thinks the Cowboysupgraded secondary will enable Ware to break Strahan’s sack record:

"He could possibly break that record this season especially with the new guys in the back covering. He might have a little bit more time to get to the quarterback. I would love to see it happen because if anybody deserves it he does."

What Spears didn't say is that an improved secondary will not just make DeMarcus Ware more effective, it will help the entire front seven play at a higher level. I would not be surprised to see a further improvement in these metrics for the 2012 team, and it's easy to see why Dan Graziano would think this unit is the Cowboys' hidden treasure.