The offensive line may be the most important part of a football team. Without the big uglies, there are no offensive heroes to cheer for. Even the best players will struggle to produce without effective pass protection or holes to run through. Yet offensive linemen rarely get noticed - except if they make mistakes.
And that is a key reason why evaluating the performance of an offensive line is not easy, simply because success is often only measured by what didn't happen: the quarterback was not sacked and the running back was not stuffed in the backfield. Traditionally, there weren't a lot of stats available to help you tell a good offensive line from a bad one.
But there are three models out there that do measure offensive line performance: BTB favorite Brian Burke of advancednflstats.com just came up with a new approach which ranks the Cowboys O-line 13th. Stats Inc., with some supah dupah top-secret formula, determined that the Cowboys were the 12th best O-line in 2010. And another favorite of ours, Football Outsiders (FO), also ranks the Cowboys O-line 12th.
After the break, we take a closer look at couple of advanced metrics from FO – Line Yards, Power Success, Open Field Yards and Stuffs - to see how the Cowboys offensive line fared in run blocking last year.
FO have their own metrics and their own terminology, and I’ve used their definitions to preface each of the statistical categories we’ll walk through below.
Adjusted Line Yards:
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 the difference in rushing average between shotgun compared to standard formations. Finally, we normalize the numbers so that the league average for Adjusted Line Yards per carry is the same as the league average for RB yards per carry [which is 4.29 yards].
They way to read these numbers is that the OL is penalized for losses (a run for -5 yards is credited with -6 yards) and gets progressively less credit for a long run: The first four yards of a run are fully credited, the next six yards (the running back hits the second level between 5 and 10 yards out) are only credited with half the yardage, for all yardage beyond the 10 yard line (the running back is now in the open field) the offensive line doesn’t get any credit whatsoever. Using Adjusted Line Yards, this is how the Cowboys offensive line performed in 2010:
||Rank||Adj. Line Yards||RB Yards||NFL Avg|
Unfortunately, FO do not publish a week-by-week number for the O-line, only an aggregate number for the entire season. This means we can't break down line performance into pre-Garrett and post-Garrett data. However, I do have the numbers through the first seven games, when the Cowboys were at 1-6. So we can see if and how the line play improved in the second half of the season. And it did.
FO ranked the Cowboys 20th through the first seven games with an ALY of 3.91 and RB Yards of 3.58. At the end of the season the unit was ranked 12th. That is a significant jump in nine games, and it's clear the OL did pick up its play in the Garret era.
The much maligned Marc Colombo credits the improved line play, especially in the running game, to the full padded practices on Wednesdays and shoulder pads only practice on Thursdays that Garrett instituted.
"I think offensive line-wise it does help because it gives us better looks," Colombo said. "Our show team, the scout team, we’re really getting good looks from them. They’re coming hard, like we see in games and it’s paying off as an offensive line. And I’m sure it’s paying off in other areas."
Overall however, the run blocking performance of the O-line has dropped versus 2009, even if there was a marked upswing towards the end of the season. No big surprise there, and some might argue that we didn't need no stinkin' stats to tell us that. That is undoubtedly true, but stick around anyway, it might still get interesting.
On average, the Cowboys offensive line cleared the path for 4.12 yards per run for the running backs, which is down by about a third of a yard versus 2009. That's not all that much, and considering where they were through the first seven games of the season, they were probably runblocking at 2009 levels toward the end of the season.
The running backs
You can have the best runblocking OL, but if your running backs have two left feet, your running game probably won't get very far. And while you can't completely separate the effect the two position groups have on each other, you can approximate it by combining running back yards and ALY. FO define running back yards as follows:
Yards per carry by that team's running backs, according to standard NFL numbers.
Per the table above, the Cowboys’ running backs gained 3.87 yards in running back yards in 2010, ranked 25th in the league. This is a drop by over a yard per run versus last year. Not good by any measure.
If you deduct the the Adjusted Line Yards from the Running Back Yards you'll get a good measure of how the running backs performed relative to the line, because by taking away the contribution of an offensive line, be it good or bad, you'll get a measure of how good a running game a team has. And this is where you could start to really worry. The table below does that calculation for the top five and bottom five teams in 2010.
Running Back Yards minus Adjusted Line Yards, 2010
|Top five Teams
||Bottom five Teams
The Cowboys are ranked 28th in the league in this measure. The Cowboys running backs combined to gain 0.28 yards on average less than the offensive line provided. At first glance this would seem to indicate that the decline in the Cowboys' overall run game this year is more a result of bad running than bad blocking. But what sounds more likely to you: that the O-line performance has suffered or that our running backs capabilities have declined?
We recently reviewed the Cowboys running backs thoroughly, so let's go off on a tangent here and revisit that review briefly using another FO metric, DVOA or Defense-adjusted Value Over Average. DVOA breaks down every single play of the NFL season to see how much success offensive players achieved in each specific situation compared to the league average in that situation, adjusted for the strength of the opponent.
|Player||'10 DVOA||'09 DVOA|
|Felix Jones||8.2% (10th)||8.9% (15th)|
|Marion Barber||-12.3% (36th)||17.0% (5th)|
-4.8% (- -)
||24.7% (- -)|
Felix Jones was a top 10 running back in 2010, while both Barber and Choice regressed significantly versus 2009. This disparity in performance from the Cowboys' three backs is a key driver for the uneven results in the running game.
I can already hear you asking "But what about all those failed short yardage and goal line attempts? And isn't the lack of longer runs by the Cowboys running backs screwing with those averages?" Thank you for those extraordinarily insightful question. On to the next set of metrics.
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.
If you think back to 2009, you'll distinctly remember that the Cowboys offensive line struggled mightily with running plays on short yardage situations, especially in goal line situations. The numbers bear this out: the Cowboys ranked 26th in power success with 58% in 2009. Not a big revelation there, but now take a look at the 2010 numbers in comparison:
||Rank||Power Success||NFL Avg|
Nothing changed. The short game is and remains the Achilles heel of the Cowboys offense. More often than not, our linemen simply cannot get enough push to clear the necessary yardage for the RBs. The difference vs 2009? Less futile attempts inside the opponent 5-yard line. Instead, the short yardage failures are spread all over the field.
10+ Yards or Open Field Yards
Yardage gained by running backs at least 10 yards past the line of scrimmage, divided by total running back carries.
FO are calling all yardage beyond ten yards ‘Open Field Yards’. If you take Open Field Yards divided by total carries, you get an indicator for ‘big play ability’, or at least ‘break away ability’ of your running game.
|Open Field Yards
||Rank||10+ Yard runs / carries||NFL Avg|
The 2010 Cowboys running game lost it's big play ability, and didn't find it again, not even under Garrett as head coach. This unit did an okay job when the task was to simply block the man in front. The tight ends and the full back would chip in and that was enough for a three or four yard run. But it's hard to break off any long runs when the line can't consistently open and hold holes to run through.
Watch any breakaway run by a back and you'll probably see a guy shooting through a hole the offensive linemen opened. If your backs are unable to get down the field with any regularity, chances are it’s the offensive linemen that are not making it happen.
For the stuffed run stats, we'll go back to the official NFL numbers. The Cowboys running game was stuffed at or behind the line of scrimmage only 31 times, which translates to 7.2% of all running plays and is good enough to rank the Cowboys eighth in the league.
The Cowboys runblocking clearly regressed versus 2009. Getting to the line of scrimmage and perhaps a couple of yards beyond wasn't the big issue for the 2010 Cowboys running game. But getting to the second level was.
The Cowboys linemen collectively simply don't move all that well anymore, and plays that require speed to pull off proved to be a hit and miss affair. Our men up front are getting old, and they are tired. Too often in 2010 we saw linemen not getting to their blocks fast enough and runners dancing around in the backfield trying to find a hole somewhere. The Cowboys linemen are some heavy dudes, and outside of Marc Colombo, they didn't get pushed around all that much. Unfortunately, they didn't do all that much pushing themselves either.
The Cowboys running didn't get stuffed very often, but seemed to hit a wall about two to three yards beyond the line of scrimmage with a frustrating regularity. Whether that was a result of bad running, bad blocking, bad playcalling or a combination of all three, that's for you to decide.
[Next up: Individual run-blocking grades as well as the impact of the near mythical Cowboys blocking tight ends on the line's performance, before we move on to a detailed assessment of the pass protection game a little later]