The Best 2010 NFL Defense: A Deeper Statistical Analysis Than Yards Per Game, Part 2

One of the fallacies that bugs me in the NFL is the definition of the top offense and defense in the NFL.  Generally, the majority of NFL fans and analysts go by yards per game.  Defensively speaking, if your team gives up the least yards per game you are crowned the best defense in the league.  It gives a simplistic view of offense and defense, but it is incredibly inaccurate and completely ignores millions of dependent variables like time of possession, points, yards per play, etc. Therefore, I decided I wanted to take a deeper look into NFL defenses and find the best one based on more than just yards per game.  I will try to take into account those many dependent variables, but remember this is not perfect science (what is really?).  This is just one man's statistical review of the issue.  I guarantee you though, it is a better representation of a defense as a whole than yards per game.

In case you missed it, see Part 1 here.

All of my numbers have been collected from Pro-Football-Reference (and a few other sources listed elsewhere).

Moving forward, there is more to defenses than just yards allowed.  A good defense can get after the QB and pile up sacks and turnovers.  Several categories I think that quantify a good defense would be sacks, QB pressures (stat from ProFootballFocus premium membership), turnovers forced, and touchdowns given up on defense.  For the purpose of being consistent and fair, I will do percentages rather than total numbers (i.e. a team that sees more pass plays is more likely to get more sacks).  Therefore, the Sk% column would be the percentage of sacks the defense gets per opponent drop back.

It is interesting to see how bad the Ravens pass rush is, because I was not expecting that with the type of year Terrell Suggs is having.  The Steelers, on the other hand, remain green in everyone of their rankings so far.  Their lowest ranking being the pass yards per game (12th).  In these four rankings, the Steelers again have the best average ranking of 3.75.  They are followed by the Packers at 7, the Patriots at 10.5, the Giants at 11.75, and the Rams at 11.25.  In dead last again, is the Broncos with an average rank of 30.

At this point, I think we can separate out a few teams into the final discussion.  I think the teams still left in the debate would be the Steelers, Chargers, Ravens, Jets, Bears, and Packers.  You could slide in the Patriots, Giants, and Eagles if you would like, but I do not think their defenses are well-rounded enough.

Finally, since the Steelers pass defense was the biggest "concern" (at least according to pass yards per game, let's break into the pass numbers even more.  Let's take a look at QB Rating, AY/A, NY/A, and ANY/A.  I explained what these numbers meant in a previous stat post, but in case you missed it let me explain.  AY/A is Adjsuted Yards per Attempt, which adjusts Y/A by adding weight for touchdowns and taking away for interceptions.  The equation is (Pass Yards + 20 * TDs - 45 * INTs) / Attempts, where the 20 and -45 are constants determined by a ton of statistical analysis.  NY/A is Net Yards Gained per Pass Attempt, which adjusts the number based on yards lost by sacks.  The equation is (Passing Yards - Sack Yards) / (Pass Attempts + Sacks).  Lastly, ANY/A, or Adjusted Net Yards Gained per Pass Attempt, is just a combination of the two.  I like these numbers better for ranking a defense because it combines several statistics into one category, which are easier to use.

This post is getting rather long, so I won't harp too much on this table.  These numbers do a good job debunking the Steelers having a bad pass defense.  Call it hiding a two bad corners with a solid pass rush if you want, but it is still damn good. The Steelers are committed to maintaining a solid pass rush, as they displayed in the 2010 NFL draft.  It should be interesting to see the effort they put into signing Ike Taylor vs. LaMarr Woodley, two very important players to this defense.

Since all of these categories are pretty similar, I averaged them for the final table to prevent them from having an overpowering weight in the final ranking (P Stats Rk).  Also, since I mentioned yards per game were worthless, I removed them from the rankings all together.  I kept all of the categories I believe quantify a good defense.

It is no surprise to me that the Steelers come out far and away the best defense of 2010 in this analysis.  It should not be a surprise to anyone who watched them play this year.  On the field you could see the tenacity of the defense that is categorized by these numbers.  In all of the categories I selected the Steelers finished in the top 6, whereas the other top defenses had at least one category that fell at or below average.