Last week I wrote briefly on whether or not the idea that “Defense Wins Championships” was a bit outdated. Looking solely at overall rankings in points per game scored/allowed, it seems as if good defenses are still a key element of a Super Bowl winning team. Of the 3 “bad” defenses which have won Super Bowls lately (2006 Colts, 2007 Giants, 2009 Saints), both the Colts and Giants got hot down the stretch to carry their team to a Lombardi trophy.
However, points per game allowed is a pretty simple measure of a defense and doesn’t tell us all that much about the unit in question. Here are some more numbers on the Super Bowl winning defenses:
Yards Per Drive Allowed
Average YPD: 26.2
Average YPD+: 108.8
Best YPD+: 1974 Pittsburgh Steelers (131)
Worst YPD+: 2006 Indianapolis Colts (79)
# of teams <100 YPD+: 8
Points Per Drive Allowed:
Average PPD: 1.36
Average PPD+: 121.6
Best PPD+: 2000 Baltimore Ravens (150)
Worst PPD+: 2006 Indianapolis Colts (75)
# of teams <100 PPD+: 1
Average TO%: 21.8%
Average TO%+: 114.8
Best TO+: 2000 Baltimore Ravens (165)
Worst TO+: 1976 Oakland Raiders (76)
# of teams <100 TO+: 9
Average TD%: 14.9%
Average TD%+: 123.2
Best TD%+: 2000 Baltimore Ravens, 2002 Tampa Bay Buccaneers (152)
Worst TD%+: 2006 Indianapolis Colts (74)
# of teams <100 YPD+: 3
As you can see, other than the 2006 Indianapolis Colts, Super Bowl defenses have remained pretty consistently above average in most of these variables. Here are the 41 Super Bowl champion defenses from 1970-2010 ranked by my Defensive Efficiency Scores:
The average DSCORE of a Super Bowl winner is 20.83. Only 2 teams in 2011 had a DSCORE that high: San Francisco and Baltimore. The 2011 Patriots checked in at 5.93 and the Giants at -4.42. However, like the 2006 Colts and 2007 Giants, both current Super Bowl teams are playing better than their regular season numbers indicate. Whichever team wins next Sunday will join the recent trend of teams whose defenses got hot at just the right time.
With the 2011 regular season in the books, here are the final efficiency scores:
|1||2||Green Bay Packers||53.95|
|2||10||New Orleans Saints||48.95|
|3||17||New England Patriots||42.35|
|5||182||San Diego Chargers||17.65|
|8||243||San Francisco 49ers||13.90|
|9||280||New York Giants||12.60|
|18||723||New York Jets||-4.50|
|29||1135||Tampa Bay Buccaneers||-26.40|
|31||1201||Kansas City Chiefs||-37.95|
|32||1209||St. Louis Rams||-40.70|
|1||20||San Francisco 49ers||36.65|
|6||270||New York Jets||12.88|
|9||324||Green Bay Packers||10.70|
|11||446||New England Patriots||5.93|
|18||621||Kansas City Chiefs||0.54|
|21||771||New York Giants||-4.42|
|25||943||New Orleans Saints||-12.46|
|26||955||St. Louis Rams||-13.10|
|27||982||San Diego Chargers||-14.61|
|32||1190||Tampa Bay Buccaneers||-34.40|
Here are the 2011 Defensive Efficiency Rankings through Week 16:
|1||12||San Francisco 49ers||40.72|
|6||268||Green Bay Packers||12.96|
|8||307||New York Jets||11.60|
|14||519||New England Patriots||3.99|
|20||781||Kansas City Chiefs||-5.04|
|21||811||New York Giants||-6.27|
|25||877||St. Louis Rams||-9.30|
|27||956||San Diego Chargers||-13.09|
|28||968||New Orleans Saints||-13.68|
|32||1185||Tampa Bay Buccaneers||-33.20|
Listening to the media and reading sports messageboards, you might get the impression that the 2011 Green Bay Packers and New England Patriots have historically awful defenses. A common claim is that neither team can win the Super Bowl unless their “offense is perfect” because their defenses are so appallingly bad. Fortunately for Packers and Patriots fans, the claim that these teams’ defenses are terrible is completely bogus.
If you checked out my 2011 Defensive Efficiency Rankings, you probably noticed that the Packers rank 8th and the Patriots 13th. That seems so far beyond the media narrative that one would be quick to dismiss my rankings as inaccurate or flawed. But taking a quick look at the numbers, it’s easy to see why these teams’ defenses score pretty well.
The big reason why my rankings are out of whack with the common perception of these teams’ defenses is that I don’t have much use for yards allowed. The Patriots and Packers are 32nd and 31st in the league in yards allowed. By this measure, both teams are horrific. The Patriots are allowing roughly 41.4 Yards Per Drive, the Packers 39.8 Just how bad are those numbers? Only 3 teams since 1970 really compare: The 2008 Denver Broncos (41.05 YPD), 2008 Detroit Lions (39.45) and the 2008 Kansas City Chiefs (39.07). The Patriots are on track to give up more YPD than any team in post-merger history, and the Packers aren’t faring too much better. The Houston Texans lead the league in YPD allowed giving up an impressive (by 2011 standards) 26.3 YPD.
That said, neither team gives up tons of points per game. In fact, both are about league average. In terms of defensive points allowed (this excludes points given up on special teams and offense) through 14 games, the Patriots have given up 287 (20.5 PPG), the Packers 291 (20.8) . League average is 292 (20.9). Since preventing points is the primary goal of a defense, the least we can say about these teams is that they are “about league average” defensively. Saying these teams are the worst in the league implies that one would prefer a team which gives up fewer yards, but more points (since those defenses would be “better”). For example, the Denver Broncos allow 31.4 YPD – a little better than league average, and significantly better than either Green Bay or New England. But they allow 22.6 points per game – 6th worst in the league.
So both teams are pretty average in the most important measure of defense – points allowed. However, both teams excel at creating takeaways. The Packers are tied with the 49ers for best in the league (forcing a turnover on 22.9% of their opponents drives) and the Patriots are 3rd in the league (20.0%). League average is 14.9%. Both teams are significantly better than league average in takeaways.
The Jacksonville Jaguars are thought to have an excellent defense – it’s 4th best in the league in yards allowed. But they only allow about one fewer point per game than the Patriots and Packers (19.6 PPG). However, the Jaguars don’t force nearly as many turnovers – on only 13.8% of their opponents drives. Furthermore, they allow points more easily – their YPP allowed is 15.6 compared to the Patriots’ 20.2 and the Packers’ 19.1.
The name of the game on defense is to prevent points and create turnovers (which can lead to points, either directly or indirectly). The Jaguars are a little better than Patriots/Packers at the former, but much worse at the latter. Which defense would you prefer? It’s not as easy of a choice as you might have thought.
With 15 weeks of the NFL season in the books, here are the OSCORE and DSCORE rankings:
|1||3||Green Bay Packers||52.35|
|2||14||New Orleans Saints||43.20|
|3||21||New England Patriots||40.05|
|4||185||San Diego Chargers||17.05|
|10||339||San Francisco 49ers||10.15|
|11||371||New York Giants||8.90|
|14||565||New York Jets||0.90|
|28||1110||Tampa Bay Buccaneers||-23.65|
|31||1192||Kansas City Chiefs||-35.25|
|32||1213||St. Louis Rams||-43.55|
|1||8||San Francisco 49ers||44.34|
|6||252||New York Jets||14.02|
|8||318||Green Bay Packers||11.18|
|12||446||New England Patriots||5.98|
|22||843||San Diego Chargers||-7.76|
|23||852||Kansas City Chiefs||-8.18|
|24||864||St. Louis Rams||-8.52|
|25||886||New York Giants||-9.74|
|27||1005||New Orleans Saints||-15.72|
|29||1115||Tampa Bay Buccaneers||-25.00|
This is the fourth post in my series discussing Defensive Efficiency Scores (D-SCORE). Here’s the first three parts if you missed them:
As with my offensive efficiency scores, I used a series of regression analyses to determine the weighting coefficients of the five variables I discussed. I then took those coefficients and multiplied a team’s performance relative to league average in each variable category. The final Defensive Efficiency Score (D-SCORE) is the sum of the five weighted variables. To summarize each variable:
Points Per Drive -The most important variable – it gives us a good idea of how good a defense is. However, as I noted in my offensive efficiency discussion, PPD is not a complete picture. Which of these defenses is better:
8 drives allowed: 8 FG’s = 3 PPD
8 drives allowed: 4 TD’s allowed, 2 punts, 2 INT’s in your opponents’ red zone = 3.5 PPD
In the first scenario, the defense allows fewer points. But their offense is likely to start all 8 of their offensive drives deep in their own territory. In the second scenario, the defense allows a few more points. However, by by forcing 2 punts and 2 INT’s inside their opponents’ 20 yard line, their offense is more likely to score points and thus the “extra” points they allow are largely (or entirely) negated. Now, these are obviously extreme and unlikely scenarios but the idea is that a team’s offensive and defensive outputs are related and the true value of a defense is the effect it has on the margin of victory.
For the purposes of these rankings, I took the “Adjusted” PPD – this factors in defensive points scored (safeties, fumble recovery and interception TD’s).
Touchdown% – Obvious point: preventing touchdowns is the most important thing a defense can do to limit the number of points they give up. The ability to frequently limit your opponent to field goals is a very valuable trait – one which every elite defense has in common. Think of it this way: the average field goal attempt allowed is worth ~2.3 points (between 2000-2010, the average FG% was 78%, which multiplied by 3 points = 2.3). The average TD is worth about 7 points (the rare extra point miss is made up for by the occasional 2 point conversion). Theoretically, a defense could give up 3 FG attempts and stay within a one touchdown point differential.
Yards Per Point Allowed – “Bend but don’t break”, it’s a somewhat useful measure of how “tough” it is to score on a defense. Elite defenses typically score very highly in YPP. It’s most useful in providing context to a team’s yards allowed. Teams whose defense look bad based on yardage stats fall into two main categories: teams who amass big leads and are willing to give up yards, but not necessarily touchdowns in exchange for time off the clock (e.g. early 1990’s Bills, current-era Patriots) and teams who are just awful defensively. The former will score well in YPP despite having ugly Yards Per Game or Yards Per Drive. The latter will typically score very poorly in YPP (and pretty much every other category).
Yards Per Drive – Only very minimal consideration is given to YPD. There have been a number of defenses which give up lots of yards but don’t allow a lot of points. Because preventing points – not yards – is the goal for a defense, yards allowed are fairly irrelevant to a discussion of defensive efficiency. However, we cannot ignore YPD completely because there are some implications for defenses which give up tons of yards:
More yards = more potential scoring opportunities. In theory, a defense which gives up very few YPD is less likely to give up a last minute (or overtime) game-losing FG than a defense which gives up tons of YPD.
Effect on field position – Giving up tons of yards might not lead to lots of points allowed, but there is reason to think that it can limit a team’s offensive output. In other words, teams which give up fewer YPD are less likely to get pinned deep in their own end of the field because their opponent will be gaining fewer yards and thus punting from a less advantageous (for the punting team) part of the field. A defense which gives up lots of YPD is hampering their offense’s ability to score quickly (or at all)
Time of possession – More yards often means more plays which means more time off the clock – another way to hamper your own offense’s ability to score. If your favorite team is tied with 5 minutes to go, and their opponent has the ball, which defense would you prefer – the one which gives up only 21 yards per drive, or the one that gives up 35 YPD? The former is more likely than the latter to get off the field quickly enough to give your offense time to get a game winning score.
Turnover% – Forcing a turnover is the best possible outcome for a defense. Not only does it satisfy the primary goal (preventing points) but it adds a secondary benefit (scoring points directly or indirectly). Often, teams who score well in YPP have a high TO%. While a high TO% doesn’t necessarily mean a great defense, it’s rare to see a truly bad defense which creates a lot of turnovers. At worst, a team with a high TO% will be about league average in points allowed.
I weighted the variables in this order:
Points Per Drive
Yards Per Point
Yards Per Drive
With all of that in mind, here are the 20 best and worst defenses since the 1970 AFL/NFL merger:
|7||1975||Los Angeles Rams||44.59|
|9||2002||Tampa Bay Buccaneers||44.12|
|16||1991||New Orleans Saints||38.83|
|18||2003||New England Patriots||37.55|
|1171||1999||San Francisco 49ers||-37.76|
|1172||1986||Tampa Bay Buccaneers||-38.23|
|1186||1980||New Orleans Saints||-47.57|
|1187||1975||New York Jets||-49.41|
|1188||1972||New England Patriots||-50.39|
You can all the scores here: Defensive Efficiency Scores