Tuesday June 30th, 2015

In our "MythBusters" series, SI.com's NFL team uses tape, statistics and conversations with some of the NFL's most knowledgeable voices to debunk storylines that have inexplicably gained traction. In this installment, Doug Farrar examines the hypothesis that just about any NFL running back can be productive behind the Dallas Cowboys' outstanding offensive line.

MYTH: Dallas' league-best offensive line can create rushing champions out of average running backs.

REALITY: The Cowboys will miss DeMarco Murray more than they think.

Though his tenure as the Dallas Cowboys' owner may be erratic at times, Jerry Jones has engaged in some fairly intelligent team-building recently. Jones and his 'Boys have taken three offensive linemen in the first round—starting with the selection of USC offensive tackle Tyron Smith in the first round of the 2011, and drafting center Travis Frederick in '13 and guard Zack Martin in '14. On top of that, they landed LSU tackle La'el Collins as an undrafted free agent this year, after he went undrafted following a legal investigation.

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And with that, Jones and his personnel lieutenants have created a line that, in its relative infancy, looks to rival the great lines the franchise had in the early- to mid-1990s, when Dallas won three Super Bowls in four seasons.

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In 2014, Dallas' line led the NFL in Football Outsiders' Adjusted Line Yards metric, which credits and debits offensive lines for the production of backs based on a number of factors, which led many people to believe that nearly any running back could be successful behind the Cowboys' line. Jones and his team will take that theory to its limits in the 2015 season, with the free-agency departure of running back DeMarco Murray to the Eagles. The long-rumored Adrian Peterson-to-Dallas move never happened, and most likely won't, which leaves the Cowboys with Joseph Randle and free-agent acquisition Darren McFadden as the two primary Murray replacements. And when you're replacing a back who led the league with 1,845 yards, you're risking much your season on the idea that you have a line that can bring something special out of players who have not yet proven to be upper-tier NFL players.

So now, the Cowboys have a primary cadre of backs that gained a total of 498 yards in 2014—27% of Murray's total. The question is, how will Randle and McFadden perform in Murray's wake? 

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Yes, Murray benefited from stellar line play more than most backs in the league. And yes, there were times when Murray could have been more decisive to the hole, or used more of his power and speed to make things happen. But the best running backs are creators—that is to say, they make things happen in adverse situations based on their physical abilities and understanding of the system they're in—and Murray is a creator. Randle, at his best to date, does not show that attribute. And McFadden hasn't been able to average 3.5 yards per carry in any of his last three seasons. Both backs are better straight-line runners than anything else, which limits what Dallas can do.

First, let's take a look at what Dallas was able to do with Murray in 2014. For those who believe that Murray was a low-powered back who needed major gaps to get anything done, this Week 4 carry against the Saints provides an interesting counter-argument. Murray times a small hole perfectly, and then breaks multiple tackles on his way to a 22-yard gain. 

There are enough plays like this in Murray's oeuvre to make one believe that he's more than a finesse back. In fact, going back to his days as a 6'0", 213-pound star for the Oklahoma Sooners, Murray has always had a sneaky-strong angle to his running style. Pro Football Focus charts Murray with 67 missed tackles caused in 2014—only Marshawn Lynch had more. 

This 15-yard touchdown against the Seahawks in Week 6 is a pretty good example of Murray's winning combination of patience and explosiveness. He heads to the right with slide protection, waits for the hole to open, darts through, causing Earl Thomas to whiff on a tackle, and takes Richard Sherman on a ride on his way to the end zone.

Now, to the inevitable and well-deserved kudos to that line on some of Murray's more explosive plays. Murray led the league in runs over 15 yards with 27, and total yards on those runs, with 619. This 51-yard run against the Redskins in Week 8 was about as perfect an example of pull-blocking by guards as you will ever see—you can almost hear the ghost of Vince Lombardi yelling about "a seal here, and a seal here, and run this play in the alley!" Kudos to cornerback Bashaud Breeland for catching up with Murray to save the touchdown, because that's about all that went right for Washington on this play.

Occasionally, when the blocking fell apart, disaster ensued, as it did on this six-yard loss against the Eagles in Week 13. Dallas' line failed to pick up a run blitz from linebacker Mychal Kendricks, and Kendricks blasted through for an easy tackle. Murray couldn't accelerate past it. Note left guard Ronald Leary, who ran right by Kendricks—we know that assignment issues can often cause these schisms, but this is a doozy.

Now, on to Randle. The third-year man out of Oklahoma State has some people believing that he can take the reins of this run game because he averaged 6.7 yards per carry in limited action (51 carries for 343 yards), but what you want to see from a top-line back is the ability to do more than blockers create. He might be able to ease into that ability, but at this point, the 6'0", 204-pound Randle needs open gaps—he's not dominant against contact.

This 38-yard run against Seattle in Week 6 was a perfect storm of slide protection and missed assignments (we're really not sure what Kam Chancellor was doing in the defensive backfield). Props to Randle for making the cut, but this play was all about the line—and a rare faceplant against the run from the best defense in the NFL.

Where Randle does succeed is in situations where he's required to speed through the hole and make quick cuts in space. We saw this when he busted loose for a 17-yard touchdown against the Bears in Week 14. Behind outstanding blocking, Randle blasts through to the second level, and abuses Chicago's secondary with a quick jump cut. Here, we see the kind of speed and agility in space that marks the best running backs of his type. 

In this system, with this offensive line, Randle can succeed, but there are legitimate questions about whether he can transcend things if there's any regression. There are also a lot of plays like this two-yard gain against the Redskins in Week 17—when Randle fails to take advantage of the blocking he's given, muddles around the line and can't seize the opportunity for more yardage. That will obviously have to change if he's to be the Cowboys' next primary back -- he'll have to learn to be more decisive in contact situations. Randle is a speed-to-power back, so immediacy is crucial to his game.

In the end, and at least until the Cowboys acquire another transcendent running back via free agency or the draft, I think their run game will resemble what the Broncos had from the mid-1990s through the early part of the new millennium. Terrell Davis was the perfect storm—a fundamentally sound and totally effective zone-blocking line paving the way for a back who could have succeeded in just about any system. That's how you get the yardage totals Davis put up in 1996 (1,538), '97 (1,750) and '98 (2,008).

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When injuries shortened Davis' career, the Broncos made do with a string of backs who probably would not have made the cut in a lot of systems without a ready-made blocking paradigm—guys like Olandis Gary, Mike Anderson and Reuben Droughns. There was a nice little stretch from 2002 through '05 when Clinton Portis displayed similar efficiency and productivity to Davis', but he was then traded to the Redskins for cornerback Champ Bailey—which, in the end, proved Portis' value to the team more than anything he ever did on the gridiron. The Broncos used the second-round pick they got in that trade on Oklahoma State back Tatum Bell, who became another one-hit wonder.

Based on Randle's tape, I see him as another one of those one-hit wonders. While he has the ability to be productive behind what has become the NFL's best run-blocking line, I do not believe he has enough of Murray's attributes to represent an immediate value replacement, but do I see him as a player who can re-define that run game in his own image. There's nothing wrong with one-hit wonder running backs. But it's up to the Cowboys to understand that until their version of Clinton Portis comes around, they just lost their Terrell Davis... and there appears to be a whole lot of Olandis Gary and Reuben Droughns right around the bend.

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