Recently, Smackdad wrote an awesome article on the New York Jets defense since 2009. The article explored the idea that the performance of a defense is influenced by the caliber of the offense, with a specific focus on turnovers. Assigning a point value for every offensive turnover is a great idea, and it made me think of other ways that a defense can be hampered by poor offensive play. I decided to take a more granular look at defensive statistics to try to get a better sense of the effectiveness of the Jets defense and to tease out the impacts of the Mark Sanchez offense. There are two metrics I want to dive into to determine what impact they may have on a defense: Defensive points per drive and defensive field position.
We will start with defensive points per game, which should be able to give us a sense of a defense's effectiveness. A defense that is continually on the field due to erratic offensive performance will be at a disadvantage when compared to a defense that is complemented by a high-powered offense. I used the website Football Outsiders (they have some great stats), and when we look at the results for the past couple of years, there is a frightening trend:
The 2009 Jets were absolutely incredible, with 28% less points allowed per drive than the 2nd best defense. Since that high point, the Jets defense has been steadily regressing over the last 4 seasons; we've gone from #1 in 2009 (by a huge margin), to #5, #6, #13, and finally #16 in 2013. While there is still cause for concern, the Jets currently sport one of the most talented defensive lines in the league. A strong showing from our partially revamped secondary could easily catapult the Jets back to the top ten in 2014. The fact that the Jets went 8-8 with a middle of the pack defense and bottom 5 offense is pretty remarkable and speaks volumes to the parity that exists in the NFL. That or the Jets caught a couple of lucky breaks. As an interesting side note, the collapse of Chicago's defense in 2013 looks shocking on paper, as they were a top ten defense between 2010 to 2012, and then fell all the way from #1 in 2012 to #31 in 2013 (maybe firing Lovie Smith wasn't such a great idea).
While the points per defensive drive sheds some light on the inefficiencies of an offense, I also think it is important to consider defensive field position to get a sense for where turnovers are occurring and the impact of special teams. The thought here is that in addition to giving up extra possessions, the Jets are consistently below-average on offense and may be giving opposing offenses better field position on a weekly basis.
The Jets average gross yards per punt is consistently in the bottom half of the league, which hurt defensive field position. However, the biggest driver of this statistic is the offense's inability to move the football (consistently in the bottom half of the league in yardage) which often forced punts from deep within our own territory. It is further exacerbated by the slew of offensive turnovers that have occurred in the past 5 years, that Mike Westhoff's special teams unit was not able to make up. With Westhoff's reputation as a special teams guru, it is fair to wonder how much worse the defensive field position would have been in 2009-2012 without him.
I really like utilizing the points per drive and field position because they show the how the defense performed, given the circumstances they faced. While a correlation between these two is fairly intuitive, I was a bit surprised to see how strongly tied together they were (e.g. SEA, CAR, SF, and KC rank in the top 6 in both categories in 2013). Let's go a step further: we can take the ranking in field position and subtract the ranking in points per drive to get an "adjusted defense" metric.
- A negative AD metric means the defense under-performed their field position, and so we assume that teams with good offenses/special teams and bad defenses will have very negative numbers. Looking at the 2013 ranking, the teams with the most negative AD metrics are Dallas, San Diego, Denver, Chicago, and Atlanta, which fits our assumption.
- A positive AD metric means the defense outperformed their field position, and so we assume that teams with bad offenses/special teams and good defenses to fit in this group. In 2013, these teams were Cincinnati, Arizona, Baltimore, the New York Jets, the New York Giants, and Buffalo, which once again fits our assumption.
If we look back through to 2009, the Jets are almost always one of the top teams in terms of overcoming bad field position on defense. This certainly isn't surprising in the Mark Sanchez turnover era, but it is reassuring to know that Rex Ryan's defense has consistently been better than conventional numbers imply. This also makes me pretty optimistic from a defensive perspective heading into 2014. If the Jets can grow on defense and improve to average defensive field position, they'll be trotting out a top ten defense every week.
Agree? Disagree? General thoughts? This is my first fanpost, so hopefully you guys like it. Let me know what you all think.