How Sean Lee Injury Affects the Dallas Cowboys Defense Heading into 2014 Season

Jonathan Bales@thecowboystimesAnalyst IMay 29, 2014

Dallas Cowboys linebacker Sean Lee is helped off the field by head athletic trainer Jim Maurer, left, and associate athletic trainer Britt Brown, right, after suffering an unknown left leg injury during an NFL football organized team activity, Tuesday, May 27, 2014, in Irving, Texas. (AP Photo/Tony Gutierrez)
Tony Gutierrez/Associated Press

When Dallas Cowboys linebacker Sean Lee tore his ACL on the first day of OTAs, it was clearly a blow to the defense in "Big D." Lee is a big-time playmaker who, when healthy, has shown the ability to dominate games.

In addition to being such an impactful player, one of the reasons the Cowboys will miss Lee is because there’s a big drop-off behind him.

The Cowboys could realistically be relying on a fourth-round rookie in Anthony Hitchens to be the keystone of their linebacker corps as the “Mike” LB, which obviously isn’t an ideal situation.

So, how much will the ‘Boys miss Lee?


Lee's Value to Dallas

Let’s start with assessing Lee’s dominance. Looking at stats from Pro Football Focus (subscription required), we see that Lee made a tackle on 12.0 percent of his snaps last season, which is a really high number.

Actually, ESPN Stats & Info indicates that only four linebackers have surpassed Lee’s tackle rate of 9.2 percent over the last four years.

Furthermore, despite all of the time he missed, not a single linebacker tallied more than Lee’s 11 interceptions in that span. He always seemed to be in the right place at the right time—a true high-IQ football player.


How Has Dallas Performed Without Lee?

One of the ways to determine how poorly off the Cowboys will be without Lee is to look at how they’ve performed in his absence in the past. Lee has missed 15 games over the past two seasons, so I looked back and compared those games to the contests in which Lee played.

First, take a look at the total first downs allowed by Dallas.

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There’s barely a difference, but Dallas has actually allowed 0.3 more first downs with Lee in the lineup as opposed to when he’s been out. That’s surprising.

Next, take a look at the yards allowed by Dallas.

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The biggest area where the Cowboys could potentially miss Lee is in the running game. His tackle rate is a reflection of his prowess as a run defender, and the Cowboys have allowed 13 fewer rushing yards per game with Lee in the lineup.

Perhaps surprisingly to some, however, the Cowboys have yielded fewer passing yards per game when Lee has been injured—24 fewer per game, actually.

That means that as a defense, the Cowboys have allowed fewer total yards per game in the 15 contests Lee missed compared to the 17 in which he played over the past two seasons.

How can that be?

You might argue that the Cowboys are just a better team with Lee in the lineup, so they win more and thus see more passing attempts as they’re leading games. That’s probably not the case, however, since the team is about equal with Lee in the lineup (9-8) as when out (7-8) in the past two years.

Moreover, there isn’t a significant difference in YPA against.


Lee Is Not an Elite Pass Defender

Lee is an All-Pro linebacker against the run and a decent linebacker in coverage. That might seem ridiculous, since Lee has a linebacker-high 11 picks in the last four years, but interceptions are notoriously volatile.

Remember cornerback Anthony Henry? He had 10 interceptions in his first NFL season, then only 10 more over the next four years.

Picks come in bunches, so grading a player’s coverage ability off them isn’t wise.

I like to use Pro Football Focus’ (subscription required) yards-per-snap metric because it gives us an idea of who is getting targeted and how well they perform when thrown at.

Here’s how many yards Lee has allowed per snap since he became a starter in Dallas.

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In 2013, Lee allowed 0.88 yards per coverage snap. That ranked him as the 24th-best linebacker in the NFL—good, but not great.

In the two years prior, however, Lee allowed an average of 1.19 yards per snap, which ranked him near the bottom of the league. If we take the average of Lee’s past three seasons, he would have ranked just 41st of 51 qualifying linebackers in 2013.

What’s likelier: A decent coverage linebacker has happened upon an above-average number of picks or an elite coverage linebacker has somehow managed to turn in below-average efficiency numbers over a three-year span?

Yes, there’s something to be said for forcing turnovers. Lee’s interceptions have been huge for Dallas.

If we’re trying to determine how good Lee is in coverage, though, the yards-per-snap metric is going to give us a better idea of Lee’s true talent. The interceptions explain how valuable he’s been in the past, but the yards allowed per snap can help determine how good he’ll be in the future.


Life Without Lee

By no means am I saying that the Cowboys will be better off without Lee. He’s an outstanding linebacker and someone the team will miss in a major way.

However, it’s not like the defense can’t overcome his absence. It’s going to hurt in the running game, but don’t expect a major change in the passing game. In terms of coverage ability, you could argue that DeVonte Holloman is already on par with Lee.

From an opponent's perspective, the only advantage of Lee’s absence is that it could dare offenses to run the ball more. They’ll probably be more efficient doing it, but forcing a team to keep the ball on the ground isn’t the worst thing in the world.

It’s difficult to say for sure how much the Cowboys will miss Lee—and they will miss him—but chances are it isn’t quite the death blow many are thinking.


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