In the 2011 preseason, it appeared that the AFC West was going to be a pretty decent division. The Chiefs, Chargers, and even Raiders were all poised to have solid years and all looked to challenge for the division title; the Chiefs were the defending champs and though they lost Big Charlie, the offense looked to just build on the previous year's success and there were stars littered all over that team. The Chargers had a brilliant offense and impressive defense in 2010, but erratic and downright miserable special teams play cost them in too many games; many pundits expected the Chargers to be the class of the division, though. And though the Raiders had changed HC yet again, the team was looking to build on the first modicum of success that they've had in some time; they could even lay claim to having "Won the Division" because, while they finished one game behind the Chiefs, the Raiders did sweep the division by a combined score of 215-to-107. Denver seemed to be in the Nuclear Winter following the mushroom cloud that was Josh McDaniels, but they had a young team and a savvy head coach and there's always hope with young talent.
As usual, the NFL doesn't follow script and the season unfolded in a vastly different way than many expected. Injuries, front office/head coaching problems, and just poor play riddled the entire division resulting in a 3 way tie at the top of the division and a winner with a .500 record (The last play Chiefs finished a mere 1 game out). So how did the defenses play into this? We all know that the Raiders defense was bad. Really bad--perhaps historically bad--for a myriad of reasons that I've detailed before and that many have discussed. But how were the defenses on the other teams in division? Denver's team was generally supported by their defense as the Teborton offense muddled away and the Chief's defense looked fantastic when they played the Raiders, but how were they when they weren't facing a QB only a couple of weeks removed from playing catch with TJ Houshmandzdeh in a neighborhood park? And the Chargers' D appears to have taken a moderate step back when Greg Manusky stepped in for the loss of Ron Rivera. Were they average or were they worse than that?
In analyzing and assessing the defenses, I came up with the following ranking of the AFC West defense, which may surprise :
This has to be a joke, right? Or at least a very biased, homer-istic opinion? How could I rank the Chargers behind the Raiders? The Chargers were a middle-of-the-pack defense, ranked #22 in scoring defense in 2011 while the Raiders were an abomination, finishing 29th in the league, some 60 points behind the Chargers. And Denver was also ranked behind the Chargers, at #24.
I used my standard methodology, which was to examine the drive results for each defensive drive that the team played. I assessed them by field position and results and constructed a mathematical model that represents the defensive performance; i refer to this as the "Defensive Signature" or the "Points per Drive"-model.
In examining the data, I used a few assumptions that help shape the model. First, I excluded all Kneeldown drives. In cases where there is a drive that consists only of one, two, or three kneeldowns, I removed that data entirely from the assessment. Second, I attributed all field goal ATTEMPTS as 3 points against the defense. The defense does not get credit for special teams play and surrendering the field goal attempt is notable. Third, TDs are all 7 points; this model does not account for 2 point conversion or missed PATs.
After building the PPD model, I aggregate the data for the drive distribution that the defenses faced. How many drives did they play and where were they located on the field. This would be key to assessing the defensive performance.
With PPD data and drive data, the total points distribution can be seen. So that the distribution of points compared to starting field position of drives can be generated. This generally follows the shape of the drive distribution.
This is all farily straightforward and mostly shows the distribution of the points; it does not re-organize the points. So what we see here is that the teams are still ranked in the same order as in the NFL's Defensive rankings, but we gain some insight into the areas in which the defenses are performing well and where they are not. In other words, this is just clarification, not assessment.
After this, there are two additional adjustment steps that do (potentially) re-rank the teams and perhaps give further insight into how well the defenses were performing overall. How good or bad are the defenses, really?
The first adjustment is called"Drive Distribution Normalization" or simply "normalization" for short. A primary driving force for this analysis is to attempt to factor out as many variables as possible, thus leaving us with numerics that can be compared reasonably. One variable that sticks out is Drive Distribution. For instance, consider two defenses. The first defense has terrible field position and half the drives occur on their side of the 50 yard line. The other defense has fantastic field position and the majority of the drives occur inside the opposing 40 yardline. The two defenses surrender the same number of points. Intuitively, we would say that the first defense was performing better than the second defense, despite defensive PRODUCTION being about the same. This is what the normalization step accounts for.
This normalization step projects what the defensive points allowed would be if the defenses were to have played against an NFL AVERAGE drive distribution. Now all teams will be ranked against a common drive distribution, eliminating a major variable.
The second adjustment is "Adjusting for Strength of Opposing Offenses" or "Offense Adjustment." We're all familiar with Strength of Schedule components in the BCS formulae (historical BCS formulae I should say as I believe recent decisions have eliminated SOS from the BCS formulae). This is similiar in concept though different in execution. Consider two defenses. The first defense faces the worst offenses in the league, teams that struggle to score. Meanwhile, the second defense facees the best offenses, like Green Bay and New Orleans, that regularly put up 30+ points. If these two defenses have the same defensive production, we would consider the second defense to have performed better than the first. That's what this adjustment accounts for.
The defenses' opponents are analyzed; the OFFENSIVE PPD Signature is taken and compared to the NFL average. The Defensive PPD signature is then assessed and adjusted with respect to the offensive performance. This is then projected against the normalization factor above and a final Project value results.
And that's the methodology.
It's not perfect. There are naturally factors that cannot be taken into account, but it should give a clearer view of what these defenses were doing and motivate discourses that are more enlightened than the strict and somewhat naive defensive rankings that we have.
There are other things we can look at and analyze, of course to gain insight into what the defenses are doing at a statistical level, but for now, this is a look at ranking these four defenses.
For a frame of reference, the NFL Average for number of drives in a 16 game season is 184. The average total points allowed is 343 points.
The model for the total points allowed is :
KC : 347
SD : 359
DEN : 373
OAK : 420
After Normalization it becomes this :
KC : 313
DEN : 347
SD : 428
OAK : 430
What happened? The Chiefs were constantly faced with substantially worse than average field position. The average drive start was the 31.3 yard line (compared to 27 for NFL Average), but this does not tell the story. They had 12 drives start inside their own 40 yardline, about twice as many as the NFL Average. There were numerous fumble and interceptions that time and time again the Chiefs' offense and special teams were putting Chiefs' defense of the field already backed up. When the drive distribution is normalized, there's a remarkable 34 point change (about 5 TDs worth). We could conclude (roughly) that the offense (and special teams as there were numerous poor punts and poor coverages) resulted in about 5 TDs on the Defenses' ledger.
Denver also found a major bump in their production number based on drive normalization. This is a bit of an indictment into what Tebow and Orton were doing to the defense. Instead of extremely poor field position, as in the Chiefs' case, the Denver offense was putting the Defense on the field far too many times. As mentioned, the NFL average for number of drives is 184. The Denver defense played 199 drives, that's about 1 extra drive per game and that gave extra opportunities for the opposition to score. When we normalize, Denver gains 26 points.
Now what is interesting is what happened to San Diego. They went from not-great-but-not-terrible 359 to an awful 428, a drop of 69 points. San Diego's drive distribution showed the inverse of both KC and Denver's drive distributions. San Diego enjoyed better than average field postion (26 yardline average starting field position) and far fewer drives (163, 21 fewer than the NFL average). This means that the Chargers' offense was effectively protecting the defense. The defense performed rather poorly when they were on the field, but the Chargers' offense managed to stay on the field and not allow the opponents to have too many opportunites.
The Raiders enjoyed slightly better than average field position and about average number of drives, a testament to the offense and Shane Lechler's punting. Unfortunately, the Raiders' defensive performance was sufficiently poor that they could take only moderate advantage of that. The result is a drop in normalized points of 10.
When adjusting for Opposing Offenses, we get this :
Chiefs : 302
Broncos : 331
Raiders : 420
Chargers : 425
Chiefs' point total drops again because of stronger than average opposing offenses. Broncos also have their score drop for the same reason. Raiders improve slightly as well. San Diego improves very slightly but not much, showing that their Strength of Offense component was very nearly NFL Average. This last adjustment moved the Raiders up just enough to edge out the Chargers for 3rd.
Now, having said all that, 5 points over the course of a 16 game season, including a number of analytic adjustment factors is well within error bounds. What that really means is that it is far from clear which defense was the worse of the two and instead, it is better to say that "it's a dead heat" for last. They are effectively about the same level of bad. However, what is interesting is that at first blush the Chargers' defense appeared to be much stronger and better than the Raiders, yet in the end it appears as if the Chargers had a very poor performing defense. As a result, Greg Manusky is out and John Pagano is in (and as we all know, Chuck B is out and JTarver is in).
What else jumps out is just how good KC's defense was. Here's a sincere hat tip to Romeo Crennel for getting that bunch--Minus Legit Stud Eric Berry --to be playing lights out despite the severe handicap that Cassel-Palko were putting them in (ints); add in some fumbles by McCluster and Charles and some awful punts by Colquitt and worse coverage units (egs., a 27 yard punt, a 38 yard punt return 7 yards, 35 yard punt returned 15 yards ) and you've got a the Defense playing in major negative position. The post-adjustment total points number of 302 is near Elite status; seriously, that's getting to where the Steelers, Ravens, and 49ers are. If Romeo keeps his fingers on the pulse of the defense (unlike his first go-round in Cleveland), the influx of talent and return of missing starters could make KC the team to beat in 2012.
Denver's defense is good and should perform much better with a true NFL offense backing them; with Von Miller ready emerge as a force and THEY look like they are going to be trouble! An interesting note is that in the Win-Loss splits (roughly correlating to the Tebow Streak), the Denver defense was ALSO performing at the 300-even point level. This defense was being dominant for extended stretches (and was absolutely abysmal at others).
And the Raiders have a total new look and new attitude; with critical stars Seymour, McClain, and Shaughnessy all returning from injuries that either ended their season or curtailed parts of it, the defense will finally be back to full strength. With Dennis Allen, who rapidly invigorated that Denver defense, taking a hands-on approach with Tarver and the defense, Raider fans are ready for a rapid ascension in 2012.
San Diego changed out their DC and spent their first 3 draft picks on defensive players; they are only 1 year removed from a very good defense and John Pagano is looking to bring it back; it's probably Norv's last year if he doesn't do something special and so there's going to be a sense of urgency there. And despite Tolbert's and Vincent Jackson's departures, I'll bet that Norv and Rivers are going to keep that offense going, meaning that they are going to continue to cover up any deficiencies in the defense.
Right now, there's alot to look forward to for ALL of the AFC West teams. We were a mediocre lot last year, but 2012 could see 2 playoff teams from the West. It's going to be a dogfight.
So there you go, Ninja Goro's look at the AFC West's defenses.
For more Ninja Goro thoughts and analyses, visit my blog at http://raiders1.ninjagoro.com/blog