DLine and Pass Defense: Myth Confirmed?

It's Super Bowl week, but debate over the draft is starting to pick up here at MHR. Much of the debate focuses on selecting a defensive line prospect or a defensive back prospect with the #2 pick. Personally, I think either one could be a great pick, because our defense was that horrid last year. The topic is of such relevance, I predict the debate will continue up until draft day.

Recently, Sharpe As a Tack wrote an article entitled "Mythbusters: Dline or Bust!" While I appreciated the attempt to bring statistics into the draft debate (The degree of intelligent discussion is one of the reasons I enjoy reading posts here at MHR), the use of the statistics in this instance was fatally flawed. Follow me after the jump as I examine why the reasoning was wrong, and an examination of statistics that would better quantify the impact drafting talent on the defensive line will have on the secondary.

The fatal reasoning in Sharpe As a Tack's article is that he assumed that a defensive line can improve a pass defense ONLY when a defensive line is associated with a strong pass defense rating. In other words, the Houston Texans defensive line could only be seen as improving the play of its defensive backfield if that defensive backfield was ranked in the top third of the NFL.

But this has never been the argument. No one is saying that the defensive backfield can be ignored and the Denver Broncos should draft "Dline or Bust." Instead, individuals have made the argument that a strong defensive line can improve the play of the defensive backfield by reducing the time the opposition's Quarterback has to throw. We're not concerned with how the Houston Texans rate compared to the rest of the NFL, we're concerned how the Houston Texans would have rated, had they not been able to pressure the Quarterback. If the Detroit Lions did not add Suh to their defensive line, would their pass defense ranked higher or lower? We're not looking for total rank, we're more interested in change.

I feel Denver Bronco fans are deeply aware of the impact a defensive line can have on a pass defense. The injury of Elvis Dumervil had a huge impact on the defense as a whole. Dumervil led the league in sacks in 2009, and the Broncos pass defense was ranked third in the league. In 2010, Denver ranked dead last in QB pressures, and our pass defense ranking dropped to twenty-fifth in the league despite the addition of defensive back talent in the draft.

But the real question we are trying to answer in this debate is, will the addition of a top rookie on the defensive line have a marked impact on the pass defense of our team?

To investigate this question, I looked at the defensive line players drafted in the top ten picks over the last five years and the change in pass defense ranking the team experienced in the player's rookie year. Below I've included the player drafted, the pass defense rank before the player was drafted, and the defensive pass ranking improvement.

Team Player Pass D Rank Pass D Rank* Improvement
Detroit Lions Ndamukong Suh 32 16 16
Tampa Bay Buccaneers Gerald McCoy 10 7 3
Jacksonville Jaguars Tyson Alualu 27 28 -1
Kansas City Chiefs Tyson Jackson 28 22 6
Green Bay Packers B.J. Raji 12 5 7
St. Louis Rams Chris Long 21 19 3
Kansas City Chiefs Glen Dorsey 5 28 -23
New Orleans Saints Sedrick Ellis 30 23 7
Jacksonville Jaguars Derrick Harvey 15 24 -9
Tampa Bay Buccaneers Gaines Adams 19 1 18
Atlanta Falcons Jamaal Anderson 29 23 6
Houston Texans Amobi Okoye 22 25 -3
Houston Texans Mario Williams 24 22



In the past five years, when teams have selected a defensive line talent with a top ten pick, 70% of the time they have also seen an improvement in their pass defense in the talent's rookie year. This is impressive considering that when teams have selected a defensive back talent with a top ten pick in the past five years, teams have seen an improvement in their pass defense 63% of the time.

The similarity of these percentages leads me to believe that adding a top cornerback or a top defensive tackle can equally lead to improvement upon the pass defense of a team. There is more than one way to skin a cat: a team can add pressure to the Quarterback, or increase their ability to cover wide receivers.

Understandably, this method is not ideal. Defensive back talent can be added with other picks or through free agency which could have a greater influence on a change in pass defense ranking. A better approach might look for more anecdotal evidence, like looking at a team like Detroit, who added defensive talent upfront but not in back, but still improved on the team's passer rating. I still think it's safe to say that a team can invest their top draft pick into a defensive line player, and still improve upon their pass defense.

Possibly even more interesting, the biggest drops in pass defense when a defensive lineman was drafted occurred with Glenn Dorsey and Derrick Harvey. Although these players are associated with a decline in pass defense, they may add credence to the theory that a strong defensive line improves a pass defense. Dorsey and Harvey could easily rank in the top five busts of the past five years, and their inability to perform could have lead to a decline in pass defense.

The Denver Broncos should be wary when selecting a prospect with the #2 pick, because drafting a bust can be so detrimental to the team. But I don't buy the theory that a cornerback is less likely to bust than a defensive tackle. I think the failures we have seen in the development of Jarvis Moss and Robert Ayers has led some Broncos fans to believe that in most cases, "Dline will Bust!" I think our front office is smart enough to not be deterred from taking a top prospect simply because of previous results, and instead invest the pick in a prospect that is versatile enough to improve both our 32nd ranked rush defense and our 25th ranked pass defense.

This is a Fan-Created Comment on The opinion here is not necessarily shared by the editorial staff of MHR

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