clock menu more-arrow no yes

Filed under:

Embrace the Numbers

New, comments

In the past, I've expressed my distaste for what people like Bill James have done to the world of baseball statistics.  Back in the late 1800s when I started caring about sports and passionately following them, baseball was about your batting averages, ERAs, home runs, RBIs, etc.  Now we have people figuring out Joe Mauer's batting average on days that start with "T" and he sleeps in half an hour later than he normally does.

(The answer to the above is "it's really high, just like his batting average is all the time."  But I digress.)

Well, now there are a couple of sites that are kind enough to do this for football.  I find these stats to be infinitely more interesting than their baseball equivalents, and much more revealing than your normal, run of the mill football stats.  We're going to take a look at how these sites interpreted the 2006 Minnesota Vikings football season.

The first site that I'm going to make reference to is Football Outsiders, a site that's on the right-hand side of the blog here under the links section, and a site that I can't possibly pimp enough.  The folks over at Football Outsiders have every team rated according to a system called Defense-adjusted Value Over Average, or DVOA.  I won't go into the entirety of what DVOA is (but if you wish to, you can find the full explanation here, but in a nutshell, here's what it is:

The majority of the ratings featured on FootballOutsiders.com are based on DVOA, or Defense-adjusted Value Over Average. DVOA breaks down every single play of the NFL season to see how much success offensive players achieved in each specific situation compared to the league average in that situation, adjusted for the strength of the opponent.

The NFL determines the best players by adding up all their yards no matter what situations they came in or how many plays it took to get them. Now why would they do that? Football has one objective-to get to the end zone-and two ways to achieve that, by gaining yards and getting first downs. These two goals need to be balanced to determine a player's value or a team's performance. All the yards in the world aren't useful if they all come in eight-yard chunks on third-and-10.

...

One of the hardest parts of understanding a new statistic is grasping the idea of what numbers represent good performance or bad performance. We try to make that easy with DVOA, because it gets compared to average. Therefore, 0% always represents league-average. A positive DVOA represents that the offense is more likely to score, and a negative DVOA represents that the defense is more likely to stop them. This is why the best offenses have positive DVOA ratings (Indianapolis in 2005: +26.9%) and the best defenses have negative DVOA ratings (Chicago in 2005: -21.8%).

Ratings for teams and starting players generally follow that scale, with the best being around 30% and the worst being around -30% (opposite for defense). However, because the baseline represents four years of play (2002-2005) no year will average exactly 0%. Over the past four years, offensive levels have bounced back and forth, so in 2002 and 2004 the league average was positive, and in 2003 and 2005 it was negative.

Team DVOA totals combine offense and defense, and the team total is given by offense minus defense to take into account that better defenses are more negative.

Got all that?

Basically, what it's saying is that a DVOA of 0% would represent an "average" offense, an "average" defense, or an "average" team, depending on the DVOA ranking (FO.com figures those separately, as well as special teams).  So, what does DVOA say about the Vikings?  Glad you asked.

We'll start with the obvious problem area of this team, that being the offense.  In 2006, the Football Outsiders ranking system shows the Vikings' offense with a DVOA value of -15.7%.  By the definition above, that means that an opposing defense was 15.7% more likely to stop the Vikings' offense than they would be to stop an average NFL offense.

That -15.7% ranking was 29th in the National Football League. . .meaning only three teams in the league were worse offensively than Minnesota.  Those three teams?  Tampa Bay (-17.9%), Cleveland (-18.2%), and Oakland (-35.5%).  What do those three teams have in common?  They'll all be picking in the Top 4 in the upcoming NFL draft.

But Football Outsiders has this broken down even further with their Premium Database, which you can currently view a free trial of.  They have this broken down into different down and distance situations, where they are on the field, different times of the game, and all sorts of other different things.  You can search anything your heart desires here, for the most part.  So, let's break this down even further, checking out the DVOA of the Minnesota offense in certain situations and how that ranked them amongst the other NFL teams.

First down:  -13.1% DVOA (24th in the NFL)
2nd down overall:  -19.8% (29th)
-2nd and short (1-3 yards):  -26.9% (31st)
-2nd and mid (4-6 yards):  -21.9% (24th)
-2nd and long (7+ yards):  -14.2% (26th)
3rd down overall:  -14.1% (26th)
-3rd and short (1-3 yards):  -1.4% (17th)
-3rd and mid (4-6 yards):  -61.2% (30th)
-3rd and long (7+ yards):  +10.8% (19th)

So. . .as should be obvious to anyone that watched the Vikings this year. . .there was really nothing at all that they did well offensively, turning in below average performances in every measurable DVOA category.  This falls pretty much in line with the NFL's official scoring stats.  As I detailed in a previous post, take away the 6 defensive/return scores that the Vikings' had this year, and their scoring average is. . .(drum roll). . .29th in the league.  Ahead of only Cleveland, Tampa Bay, and Oakland.

But enough about the miserable state of the offense.  Let's look at the side of this team that gives us a little reason for hope. . .Mike Tomlin's defense.

Now, your average fan will look at the Vikings' defense and say "OH MY GOD, THEY WERE SO HORRIBLE AGAINST THE PASS, LOOK AT ALL THOSE YARDS!!"  And, yes, nobody gave up more passing yards this year than Minnesota.  However, ranking pass defenses on their yards allowed is idiotic.  Just like in 2005 when Green Bay had the "#1" pass defense in the NFL (and believe me, nobody was buying that), the Vikings' pass defense is nowhere near the worst in the league.

As a matter of fact, the Vikings' defense was the 4th best in the NFL, according to the DVOA ratings, clocking in with a DVOA of -10.5%.  The only 3 teams that were better?  Baltimore (-25.6%), Chicago (-20.3%), and Jacksonville (-17.7%).  So, as we already know, the Vikings' defense is pretty darn good.  But, let's do a little breakdown like we did for the offense and see exactly how good they were in particular situations.

First down: -20.0% (4th)
Second down overall:  -5.9% (12th)
-Second and short (1-3 yards):  -36.7% (1st)
-Second and mid (4-6 yards):  -7.7% (16th)
-Second and long (7+ yards)  8.3% (20th)
Third down overall:  1.2% (13th)
-Third and short (1-3 yards):  -30.0% (2nd)
-Third and mid (4-6 yards):  -23.9% (11th)
-Third and long (7+ yards):  57.7% (27th)

This illustrates what many people have been saying all along. . .

  1. Mike Tomlin's defense is pretty damn good, and
  2. This defense is a pass rusher (or two) away from being elite, if it isn't already.
My pick for a pass rusher that should be readily available in free agency?

Hey. . .I can't give everything away in one column.  (-:

Once again, thanks to Football Outsiders for providing the stats.  If you really want to get in-depth when it comes to football analysis, there's no better site you can go to, in my opinion.

More Vikings news and/or other random, miscellaneous stuff as the week goes on.  Take care, everyone!