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# Rob's Mob: How The Cowboys' Defensive Line Is Dominating Games

At the beginning of training camp this year, Rob Ryan called his defensive linemen 'Bullies':

"I've got three bullies over there waiting for Thursday," Rob Ryan said. "These are proven players, and that's what we need. I don't know if we win the all-hype team, I think that might have gone to somebody else, but we're going to beat their ass when we play them."

Those comments initially drew derisive sneers and profanity-laden tirades from opposing fans. Nobody is laughing anymore, especially not the people who laughed the loudest.

Do you know how many teams have rushed for more than 100 yards against the Cowboys this season? Zero, nada, zilch. The Cowboys have held their opponents to less than 100 yards in every game so far. In fact, the Cowboys have allowed a league-low 61.8 rushing yards per game. Yes, you read that correctly: The Cowboys have the best run defense in the league right now.

Earlier this week, we looked at how the Cowboys' young offensive line held up so far this year. Today, we're going to use many of the same metrics we used to evaluate the O-line to look at how the defensive line has been doing. If you're a Cowboys fan, you'll like what you're about to see.

Once again we'll use the advanced metrics provided by Football Outsiders to look at the defensive - Line Yards, Power Success, Open Field Yards, Stuffs and Sack rate - to see just how far Rob's Mob has moved on from last year's unit.

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' defensive line performed so far this year, and how that compares to 2010:

 Year Rank Adj. Line Yards RB Yards NFL Avg 2010 22 4.27 4.40 4.18 Wk 5, 2011 3 3.50 2.99 4.31

The Cowboys' defensive line is the third best unit in terms of adjusted line yards (ALY) so far this year. This means that the opposing offensives lines have found it particularly hard to create some push against the Cowboys in the run game. The 3.5 yard ALY average is almost a full yard below the 4.31 league average. That in itself is pretty remarkable for a unit that ranked 22nd in this stat category a year ago, but what makes these numbers even more impressive are the 2.99 Running Back yards allowed.

Running Back Yards

If a defense allows less running back yards than ALY, that means one of two things: Either the opposing running backs simply aren't any good and can't take advantage of the (little) push their offense is generating. Or the defense is regularly getting to the running backs behind the O-line.

In the Cowboys' case, these numbers are highly indicative of not only a strong defensive line but also of linebackers and defensive backs who are willing and able to regularly make tackles. 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.

The low number of RB yards are a clear indicator that the Cowboys are making a lot of tackles in the backfield and that on the few occasions where a runner gets past the defensive line, the Dallas linebackers and defensive backs are good at pursuit and tackling.

Stuffed

The Cowboys defense stuffed the opposing runner at or behind the line of scrimmage on every fifth run, or 21% of the time, which ranks the Cowboys 12th 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

In both categories, the Cowboys defense is outstanding. Rob's Mob is ranked is the top-ranked unit in terms of second level yards and is ranked second behind the only 49ers (who have Patrick Willis enforcing the no-run zone in San Francisco) in open field yards.

 Year Second level yards Second level rank Open field yards Open field rank 2010 1.10 14 0.87 19 wk 5 2011 0.67 1 0.08 2

Both stats are a significant improvement over last year. Part of this improvement is due to Sean Lee smacking people to the ground left and right. But a bigger part of the credit must go to Rob Ryan, both for his new scheme and for energizing a cast that has remained largely unchanged from the previous year.

The Cowboys have 13 sacks in four games. Because other teams have played more games, the Cowboys have lost their spot at the top of the sacks leaderboard. What FO do with this metric 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 seventh with an adjusted sack rate of 8.3%, up from 11th last year.

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.

When something looks too good to be true, it usually is. For all the great stats we've seen for the defensive line above, the line still has a way to go in blocking short yardage attempts.

 Year Rank Power Success NFL AVG 2010 29 70% 61% wk 5 2011 28 83% 62%

The Cowboys' defensive line has lost 83% of their short yardage stands on third or fourth down, or on the goal line. This is one reason that the Cowboys third down conversions allowed remain at a middling 38% and have the Cowboys ranked 15th in the league. And it is an area that Ryan and defensive line coach Brian Baker need to work on. Because when it's one-on-one on the goal line, there is little room for subterfuge, for unorthodox lineups or other surprises - the bullies simply have to earn their name.

So, despite all the accolades we've heaped on Rob's Mob and their great overall performance so far, when it's third and short, you'd better hold on to your beer real tight - it's going to be a bumpy ride.