Saturday, April 12, 2008

Dissecting Denver's Pass Protection

Headed in to week 15 last season, Denver had a disappointing 6-7 record. In a road stretch against Houston (on TNF) and San Diego, getting back to .500 to dampen our disappointment weighed heavy on the minds of Broncos fans. Disaster struck. Denver was walloped in both games as Cutler constantly succumbed to pressure; sacked 9 times, Denver's offensive line seemed incapable of keeping our franchise quarterback upright. The timing of this traumatic stretch seems to have taken an inexorable toll on Broncos fans: offensive line is largely viewed as the principle need of the organization. Echoing the sentiment of many fans, one Rocky Mountain Fever commenter recently argued the following:

"I have to disagree with your false comfort regarding our O-line. They were absolutely dominated in multiple occasions (Texas, SD x2, Green Bay, Chiefs, Raiders and Detroit) and had Cutler throwing off of his back foot all season. We need to follow the success of past Super Bowl champion teams (ie Gary Zimmerman) and build around our franchise QB...I am not at all comfortable with our O-line situation when the most important position's current choices are a natural Guard, 3rd round pick with no playing experience and an undrafted Pears who failed at the RT spot last year." -the1one


With the most talented crop at offensive tackle the NFL has seen in years, it seems logical that we'd grab the top guy in the first round, right? Well, as I've argued many times, I don't think that's the solution. Far and away, the largest criticism of my opinion is that Denver's offensive line is an ineffective pass blocking unit. In this article, I'm going to evaluate the performance of our offensive line from a statistical standpoint and make some inferences about the strength of our unit.

There are some difficulties in evaluating the sacks a given quarterback suffered in a given season. First, not all quarterbacks play all 16 games. Second, some systems--like Philadelphia--will pass the ball 65% of the time; others--like Denver--tend to be a little more run heavy. Given these tendencies, there are fewer opportunities to sack a quarterback in the latter vs. the former. To normalize these concerns, I decided to focus on two statistics: sacks per game and attempts per sack (aka "sack rate"). Of these two, attempts per sack is perhaps the most useful because it is the closest thing to a sack rate we can decipher using simple statistics. To simplify the list, I only included Quarterbacks who made at least 8 starts and at least 200 pass attempts. Here's the data:


You can also download a .pdf version here and a spreadsheet with all regression results here.

Looking at these numbers, a couple of things become clear:
  • Cutler's pass protection was not abysmal last year, as some have argued, but rather only very average. He ranked 15th in attempts/sack and 17th in sacks/game. I might point out, however, that when controlling for the horrendous meltdown in weeks 15 and 16, Cutler was sacked only 1.3 times per game or once every 22 pass attempts. These adjustment catapult Cutler into the top 10 in both categories.

    I suspect the reflexive reaction of naysayers will be to claim that the poor performance coincides with the injuries sustained to the offensive line (and by extension that we can expect to get worse, without upgrading in the draft). That's simply not true. Lepsis, Nalen, and Hamilton were all long gone by mid-October. Over the next 10 weeks, Denver faced 8 of the top 15 pass rushes (5 of them top 10) in the NFL. In all but those two games, the offensive line play was exceptional, allowing no more than 2 sacks in any game.

  • While the list of sack rate leaders is top heavy with pro bowlers, there certainly are some exceptions to this trend. By far worst on the list, Ben Roethlisberger was sacked once every 6.8 pass attempts (more than thrice a game) despite boasting the leagues second-best QB rating. Despite having Walter Jones pass blocking, Matt Hasselbeck hit the turf more than his 28 touchdowns and 91.4 passer rating might suggest. David Garrard, despite throwing only 3 interceptions and boasting a 102.2 passer rating, was also sacked at a higher rate than Cutler.

    Thus, being average in these metrics is arguably not an unmanageable situation. As the1one points out, however, in a division with Jared Allen, Sean Merriman, and perhaps Vernon Gholston, Denver might have to take the left tackle position a little more seriously than the "average" team. That's fair criticism; but I'm not sure that convinces me we should spend 12th-pick money on an answer--or that the answer isn't necessarily on our roster.


Next, I want to take a look at some qualitative data on the source of our sack totals. Let's start with some data; here's a list of every player that sacked Jay Cutler in 2008:

BUF DT James McCargo: 1.0 sacks
OAK DT Gerrard Warren: 1.0 sacks
OAK S Michael Huff: 1.0 sacks
JAC DRE Reggie Hayward: 1.0 sacks
IND DRE Dwight Freeney: 1.0 sacks
PIT ILB Jerome Harrison: 1.0 sacks
PIT LOLB Lamar Woodley: 1.0 sacks
GNB DLE Aaron Kampman: 3.0 sacks
DET DT Shaun Rogers: 1.0 sacks
DET LOLB Ernie Sims: 0.5 sacks
DET DLE Jared Devries: 0.5 sacks
KAN RDE Jared Allen: 1.0 sacks
TEN FS V. Fuller: 1.0 sacks
CHI DRE Adwale Ogunleye: 2.0 sacks
OAK DLE Jay Richardson: 1.0 sacks
KAN DT Tambia Hali: 1.0 sacks
HOU DRE Mario Williams: 3.5 sacks
HOU DRE N.D. Kalu: 1.5 sacks
SDG LOLB Shaun Phillips: 1.0 sacks
SDG DLE Igor Olshansky: 1.0 sacks
SDG DRE Luis Castillo: 1.0 sacks
SDG SS Clinton Hart: 1.0 sacks
MIN ROLB Ben Leber: 1.0 sacks

(bold-type players faced Denver after Lepsis's season-ending injury)

Players in bold are those that logged sacks after Lepsis was lost against Jacksonville. Again a couple of things stand out:

  • Only 9 of Cutler's 27 sacks were allowed to defensive right ends. 5 of these were delivered by Mario Williams and his backup N.D. Kalu. Clearly that game was an abomination; however, don't discount the possibility that it was also an anomaly. Denver faced 11 of the top 15 pass rushes in the league last season. Despite this, our sack totals are pretty average. The list of right ends that managed to bring Cutler down:

    Dwight Freeney (1)
    Adwale Ogunleye (1)
    Mario Williams (3.5)
    Luis Castillo (1)
    N.D. Kalu (1.5)
    Jared Allen (1)


    It's hard to get upset about that list. Some of these guys are going to get their sacks no matter who you have back there.

  • Here's a breakdown of sacks allowed by DT, LRE, and SS/LB/CB:

    DT: 4 sacks
    LRE: 5.5 sacks (3.0 by Aaron Kampman)
    SS/LB/CB: 8.5 sacks (nobody has more than 1.0 sack)


    This data seems to argue that we were most susceptible against the blitz. To me, this is a gleaming endorsement of our need to draft a capable pass-blocker at running back, not at tackle. Travis Henry was supposed to be that guy; when he's healthy, maybe he is, but I certainly didn't see it last year and have considerable doubts about his durability headed into 2008.


There's no doubt that Denver will address their need for offensive line depth on draft day. The popular assertion that Denver will reach for a tackle in the first round based on a perceived positional need lacks historical, statistical, or qualitative credibility. A bigger need may ultimately be the selection of a third-down back with the versatility to serve as a potent offensive weapon and a capable pass protector.

In two weeks, we shall see...

3 comments:

Chris Peregrine said...

Totally Spot on. I've always felt that its been been the lack of decent blocking from the backs, failing to pick up the blitz that is the real problem. However, I'm still on board with us taking a franchise LT at #12 if such a player falls to us. What the stats don't show is performance in key situations (such as 3rd down) when the pressure's on, and one should also realise that the LT tends to get more help than the RT in pass-prot.

Michael said...

Should a "franchise" tackle drop to us at 12, I wouldn't be opposed to taking that player either. The problem is, I'm unconvinced that Williams, Otah, or Clady are that guy. Albert seems to be the next best thing to long, and he's only a sure thing at guard.

The draft analysts who predict Denver will grab a tackle are conjecturing as such based on the misconception that Denver is somehow desperate at offensive tackle. This article basically says, "no, we aren't." In fact, we've got a triumvirate of 25-and-younger players at present. Center and guard are arguably bigger "need" positions.

That wouldn't prevent me from taking a tackle if that player provided the most value; however, using the same logic you can also argue that Leodis McKelvin, Keith Rivers, Derrick Harvey, or Rashard Mendenhall are strong possibilities. None of these positions are wanting of depth, but all would benefit from another pro-bowl caliber addition.

Thanks for commenting!

Michael said...

There is undoubtedly a lot of subjectivity that isn't captured by this data. What's more, it's difficult to find accurate statistics on hurries, offensive line quality vs. quarterback ability, etc. If you look at the spreadsheet I attached, I regressed QB rating on both sack rate and sacks per game. Neither was statistically correlated.

I do think that this data is enough to overwhelm arguments that Denver's pass protection was "horrible" last year. A huge mark in favor of this article is Cutler: among Shanahan's biggest complaints of Cutler was his reluctance to check down under pressure. He holds onto the ball too long, albeit sometimes with fantastic results.

I could definitely do more with this. I'm a little more interested in this claim by many that a first round tackle will surely improve our line. I'm not convinced that a Ryan Harris has a statistically lower chance of making an impact than a top 10 tackle. I'm going to try and look at that before April 26th.

Thanks again for commenting. I appreciate the feedback!