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Defense Wins Championships? Part II

January 30, 2012 Leave a comment

Last week I wrote briefly on whether or not the idea that “Defense Wins Championships” was a bit outdated.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

 

Turnover %

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

 

Touchdown %

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.

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Passer Rating and Points Allowed

January 5, 2012 Leave a comment

Less than 48 hours from now, the 2011 NFL playoffs will begin and much of the media hype and speculation will revolve around the high-octane passing attacks of the Saints, Lions this week and the Packers and Patriots next week. Indeed, this has been a season that has revolved around the passing game. Drew Brees and Tom Brady both topped Dan Marino’s 1984 record for most passing yards in a season. Aaron Rodgers set the NFL’s single season QB Rating record and Matthew Stafford threw for 5,038 yards and a 97.2 passer rating. Not surprisingly, these 4 teams were the top 4 teams in the NFL in offensive points scored. How closely is passing success related to points scored? Consider this: of the top 10 scoring offenses, all but 2 (Carolina and Houston) threw for over 4,100 yards. Of the 10 worst scoring offenses, none threw for more than 3,800 yards, and 4 threw for under 3,000 yards.

In today’s NFL, it’s tough to be a top scoring offense without throwing the ball with a lot of success. Therefore, we’d expect teams who can stop the pass to allow the fewest points. Here is how it looks in graphical form:

As you can see, there’s definitely a correlation between the passer rating a defense allows and the points per game it gives up (note: this is defensive points per game allowed, it excludes kick/punt return TD’s and points scored against the offense). The R2 is .62. In other words, about 62% of the variance in points allowed is due to passer rating allowed.

Another way to look at it is to divide the passer rating by the PPG. This gives us a league average of 4.14 – for every 4.14 points of passer rating allowed, a defense will yield one point on defense per game. I call this PTP (Points to Passer Rating). Here’s PTP over the last 41 years:

What stands out here is the brief spike in the early 90’s. As I mentioned in my series on offensive efficiency, the NFL saw a (very) brief “dead ball” era of about 3 or 4 years where offenses slowed down a bit compared to their output in the late 1980’s. For 2011, the team with the best PTP was the Pittsburgh Steelers (5.23). The worst was the Oakland Raiders (3.33).

If you’re curious, here are Passer Rating and PPG allowed since 1970:

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Final 2011 Offensive and Defensive Efficiency Scores

January 3, 2012 Leave a comment

With the 2011 regular season in the books, here are the final efficiency scores:

Offense:

2011 All Time Tm OSCORE
1 2 Green Bay Packers 53.95
2 10 New Orleans Saints 48.95
3 17 New England Patriots 42.35
4 144 Carolina Panthers 20.45
5 182 San Diego Chargers 17.65
6 198 Detroit Lions 16.40
7 202 Atlanta Falcons 16.25
8 243 San Francisco 49ers 13.90
9 280 New York Giants 12.60
10 348 Dallas Cowboys 9.85
11 365 Houston Texans 9.10
12 490 Minnesota Vikings 3.60
13 503 Baltimore Ravens 3.20
14 626 Philadelphia Eagles -1.70
15 675 Oakland Raiders -3.10
15 675 Miami Dolphins -3.10
17 681 Pittsburgh Steelers -3.25
18 723 New York Jets -4.50
19 733 Cincinnati Bengals -4.85
20 739 Tennessee Titans -5.25
21 771 Buffalo Bills -6.10
22 865 Seattle Seahawks -10.10
23 919 Arizona Cardinals -12.95
24 993 Chicago Bears -16.65
25 1012 Denver Broncos -17.25
26 1035 Washington Redskins -18.60
27 1096 Cleveland Browns -22.80
28 1108 Jacksonville Jaguars -23.50
29 1135 Tampa Bay Buccaneers -26.40
30 1149 Indianapolis Colts -27.80
31 1201 Kansas City Chiefs -37.95
32 1209 St. Louis Rams -40.70

Defense:

2011 All Time Tm DSCORE
1 20 San Francisco 49ers 36.65
2 84 Baltimore Ravens 25.11
3 135 Seattle Seahawks 20.17
4 195 Houston Texans 16.48
5 211 Chicago Bears 15.81
6 270 New York Jets 12.88
7 300 Detroit Lions 11.78
8 314 Pittsburgh Steelers 11.42
9 324 Green Bay Packers 10.70
10 404 Jacksonville Jaguars 7.44
11 446 New England Patriots 5.93
12 465 Atlanta Falcons 5.42
13 514 Tennessee Titans 4.11
14 565 Cincinnati Bengals 2.28
15 575 Miami Dolphins 1.94
16 578 Cleveland Browns 1.88
17 620 Philadelphia Eagles 0.56
18 621 Kansas City Chiefs 0.54
19 637 Dallas Cowboys 0.13
20 644 Arizona Cardinals -0.08
21 771 New York Giants -4.42
22 781 Denver Broncos -4.86
23 915 Washington Redskins -11.14
24 921 Buffalo Bills -11.45
25 943 New Orleans Saints -12.46
26 955 St. Louis Rams -13.10
27 982 San Diego Chargers -14.61
28 1019 Oakland Raiders -16.24
29 1089 Minnesota Vikings -21.47
30 1110 Indianapolis Colts -24.07
31 1137 Carolina Panthers -26.99
32 1190 Tampa Bay Buccaneers -34.40

Defensive Efficiency Rankings Through Week 16

December 28, 2011 Leave a comment

Here are the 2011 Defensive Efficiency Rankings through Week 16:

2011 All Time Tm DSCORE
1 12 San Francisco 49ers 40.72
2 79 Baltimore Ravens 25.70
3 131 Seattle Seahawks 20.63
4 167 Houston Texans 17.88
5 191 Detroit Lions 16.83
6 268 Green Bay Packers 12.96
7 291 Chicago Bears 12.13
8 307 New York Jets 11.60
9 370 Pittsburgh Steelers 8.97
10 465 Dallas Cowboys 5.38
11 495 Cincinnati Bengals 4.62
12 501 Tennessee Titans 4.53
13 515 Jacksonville Jaguars 4.03
14 519 New England Patriots 3.99
15 584 Atlanta Falcons 1.65
16 635 Arizona Cardinals 0.09
17 646 Miami Dolphins -0.22
18 649 Cleveland Browns -0.34
19 709 Philadelphia Eagles -2.27
20 781 Kansas City Chiefs -5.04
21 811 New York Giants -6.27
22 826 Denver Broncos -6.96
23 830 Buffalo Bills -7.10
24 875 Washington Redskins -9.15
25 877 St. Louis Rams -9.30
26 947 Oakland Raiders -12.59
27 956 San Diego Chargers -13.09
28 968 New Orleans Saints -13.68
29 1075 Carolina Panthers -20.47
30 1116 Indianapolis Colts -24.99
31 1132 Minnesota Vikings -26.56
32 1185 Tampa Bay Buccaneers -33.20

The Patriots and Packers Do Not Have Terrible Defenses

December 21, 2011 Leave a comment

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.

2011 Efficiency Rankings Through Week 15

December 20, 2011 Leave a comment

With 15 weeks of the NFL season in the books, here are the OSCORE and DSCORE rankings:

2011 All Time Tm OSCORE
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
5 215 Detroit Lions 15.05
6 231 Atlanta Falcons 14.50
7 241 Dallas Cowboys 14.05
8 252 Carolina Panthers 13.65
9 301 Houston Texans 11.70
10 339 San Francisco 49ers 10.15
11 371 New York Giants 8.90
12 524 Baltimore Ravens 2.10
13 533 Minnesota Vikings 1.90
14 565 New York Jets 0.90
15 672 Buffalo Bills -2.90
16 673 Cincinnati Bengals -2.95
17 687 Oakland Raiders -3.55
18 688 Philadelphia Eagles -3.55
19 700 Pittsburgh Steelers -3.85
20 702 Miami Dolphins -3.90
21 771 Tennessee Titans -6.10
22 840 Seattle Seahawks -9.05
23 858 Chicago Bears -9.90
24 865 Denver Broncos -10.05
25 931 Arizona Cardinals -13.25
26 1056 Washington Redskins -19.75
27 1076 Cleveland Browns -21.05
28 1110 Tampa Bay Buccaneers -23.65
29 1129 Jacksonville Jaguars -25.70
30 1138 Indianapolis Colts -27.00
31 1192 Kansas City Chiefs -35.25
32 1213 St. Louis Rams -43.55
2011 All Time Tm DSCORE
1 8 San Francisco 49ers 44.34
2 106 Baltimore Ravens 22.88
3 145 Seattle Seahawks 19.38
4 151 Chicago Bears 18.92
5 157 Houston Texans 18.32
6 252 New York Jets 14.02
7 275 Detroit Lions 12.80
8 318 Green Bay Packers 11.18
9 403 Atlanta Falcons 7.46
10 427 Dallas Cowboys 6.64
11 431 Pittsburgh Steelers 6.44
12 446 New England Patriots 5.98
13 453 Tennessee Titans 5.74
14 530 Miami Dolphins 3.56
15 552 Jacksonville Jaguars 2.94
16 589 Cincinnati Bengals 1.56
17 662 Cleveland Browns -0.76
18 673 Arizona Cardinals -1.18
19 735 Philadelphia Eagles -3.18
20 752 Washington Redskins -3.54
21 814 Denver Broncos -6.48
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
26 948 Buffalo Bills -12.66
27 1005 New Orleans Saints -15.72
28 1024 Oakland Raiders -16.54
29 1115 Tampa Bay Buccaneers -25.00
30 1127 Carolina Panthers -25.98
31 1143 Indianapolis Colts -27.38
32 1152 Minnesota Vikings -28.44

Final Defensive Efficiency Rankings

December 17, 2011 Leave a comment

This is the fourth post in my series discussing Defensive Efficiency Scores (D-SCORE). Here’s the first three parts if you missed them:

Defensive Efficiency: Points Per Drive And Touchdown %

Defensive Efficiency: Yards Per Point Allowed and Yards Per Drive

Defensive Efficiency: Turnover%

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

TD%

TO%

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:

Rank Year Team DSCORE
1 2000 Baltimore Ravens 54.38
2 1970 Minnesota Vikings 50.92
3 1971 Minnesota Vikings 47.82
4 1972 Pittsburgh Steelers 46.22
5 1977 Atlanta Falcons 45.28
6 1986 Chicago Bears 44.85
7 1975 Los Angeles Rams 44.59
8 1976 Pittsburgh Steelers 44.22
9 2002 Tampa Bay Buccaneers 44.12
10 1985 Chicago Bears 42.78
11 2006 Baltimore Ravens 40.75
12 2001 Chicago Bears 40.56
13 1972 Miami Dolphins 40.05
14 1984 Denver Broncos 39.82
15 1988 Minnesota Vikings 39.12
16 1991 New Orleans Saints 38.83
17 2005 Chicago Bears 37.86
18 2003 New England Patriots 37.55
19 2008 Baltimore Ravens 36.99
20 1973 Minnesota Vikings 36.97
Rank Year Team DSCORE
1170 1984 Houston Oilers -37.68
1171 1999 San Francisco 49ers -37.76
1172 1986 Tampa Bay Buccaneers -38.23
1173 1973 Philadelphia Eagles -38.33
1174 2001 Indianapolis Colts -38.46
1175 1992 Atlanta Falcons -38.50
1176 1999 Cleveland Browns -38.54
1177 1977 Seattle Seahawks -39.45
1178 2005 Houston Texans -39.58
1179 2008 Detroit Lions -40.13
1180 1982 Baltimore Colts -40.42
1181 1971 Buffalo Bills -40.56
1182 2008 Denver Broncos -40.69
1183 2000 Arizona Cardinals -40.83
1184 1973 Houston Oilers -41.44
1185 1976 Seattle Seahawks -45.52
1186 1980 New Orleans Saints -47.57
1187 1975 New York Jets -49.41
1188 1972 New England Patriots -50.39
1189 1981 Baltimore Colts -60.74

You can all the scores here: Defensive Efficiency Scores

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