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Defending Reality: Team Defense Scoring

A deeper look at fantasy scoring for team defenses.  

Nearly every Fantasy League has different rules for how to score a Team Defense. Many use the tried and true method of one point for a sack and two for a turnover. To add a little variety, many also add six points for the rare touchdown and yet another two for the rarest of scores - a safety. Other leagues try to tweak this scoring method by incorporating points against, yards against, or both.

FANTASY FOOTBALL SCORING - A HISTORY LESSON

The basis for fantasy scoring comes from an attempt to quantify an individual player's performance numerically and assign that a value proportional to his team's performance. Touchdowns and yardage usually translate to team success, and the offensive player is rewarded for such productivity.

The second iteration of fantasy scoring came about as an attempt to normalize different positions to a similar scoring system. Quarterbacks produce more touchdowns and yardage than running backs, who produce even more than wide receivers. The result for many leagues was to reduce the points for passing touchdowns and also passing yardage so as to make running backs more valuable. Other leagues go one step further by awarding an extra point per catch to each player to increase wide receiver and tight end values closer to running backs.

What does any of this have to do with Team Defense? I am glad that you asked that question. This article is an attempt to determine how to quantify Team Defense scoring in a manner that reflects the impact a defense has on the outcome of a game, and also to provide a normalized score for a Team Defense that puts the value of a Defense at or near par for other fantasy football positions.

BASELINE DEFENSE

First, we have to determine what constitutes a good Team Defense. Is it one that gives up the fewest yards, or the fewest points? An argument can be made for either being the case, so let's take a look at the rankings from last year to see which method more accurately reflects a successful season. The results for last season are in Table 1:

Team Yds Vs Rk Pts Vs Rk Avg Rk
New England Patriots 8 1 4.5
New York Giants 10 2 6
Seattle Seahawks 5 3 4
Denver Broncos 4 4 4
Dallas Cowboys 14 5 9.5
Minnesota Vikings 3 6 4.5
Kansas City Chiefs 24 7 15.5
Cincinnati Bengals 17 8 12.5
Baltimore Ravens 7 9 8
Pittsburgh Steelers 12 10 11
Houston Texans 1 11 6
Philadelphia Eagles 13 12 12.5
Detroit Lions 18 13 15.5
Arizona Cardinals 2 14 8
Tampa Bay Buccaneers 23 15 19
Buffalo Bills 19 16.5 17.75
Tennessee Titans 20 16.5 18.25
Miami Dolphins 29 18 23.5
Washington Redskins 28 19 23.5
Oakland Raiders 26 20 23
Green Bay Packers 22 21 21.5
Indianapolis Colts 30 22 26
Los Angeles Rams 9 23 16
Chicago Bears 15 24 19.5
Jacksonville Jaguars 6 25 15.5
Carolina Panthers 21 26 23.5
Atlanta Falcons 25 27 26
New York Jets 11 28 19.5
Los Angeles Chargers 16 29 22.5
Cleveland Browns 31 30 30.5
New Orleans Saints 27 31 29
San Francisco 49ers 32 32 32

Table 1: Baseline Defense Rankings

Upon further review of Table 1, four of the Top 5, five of the Top 7 and seven of the Top 11 teams in Points Against were in the 2016 playoffs - and three of the four teams not in the top half of this category (Miami, Oakland, Green Bay but not Atlanta) all had better rankings in Points Against than in Yards Against.  Just like in the past, it appears that Points Against is a better indicator of a good defensive team than just looking at the yardage. We shall adopt Points Against as the baseline for Team Defense.

SACK THE SACK

The most common scoring system for Team Defense awards a point for every sack. This seems like a good idea, since it is an accomplishment by the defense to stop the offense from moving downfield, and it is an easy statistic to track. However, how realistic is this as a measure of Team Defense? Do sacks truly translate to team victories?

We obviously need some way to test this idea. Turning to statistics, we find that correlation is a measure of how two groups of statistics relate to one another. The formula used for correlation gives an answer between 0 and 1, with 1 representing a perfect match - 100% correlation. We can use this to see if sacks line up with our baseline, the Baseline Ranking (Points Against) from Table 1.

Table 2 lists the Team Defense rankings for sacks and the Baseline Ranking from Table 1. The correlation factor is given at the bottom of the table.

Team Pts Vs Rk Sacks Sacks Rank
Arizona Cardinals 14 48 1
Carolina Panthers 26 47 2
Denver Broncos 4 42 3.5
Seattle Seahawks 3 42 3.5
Minnesota Vikings 6 41 5
Green Bay Packers 21 40 6.5
Tennessee Titans 16.5 40 6.5
Buffalo Bills 16.5 39 8
Pittsburgh Steelers 10 38 10
Tampa Bay Buccaneers 15 38 10
Washington Redskins 19 38 10
Chicago Bears 24 37 12
Dallas Cowboys 5 36 13
New York Giants 2 35 14.5
Los Angeles Chargers 29 35 14.5
Atlanta Falcons 27 34 17
New England Patriots 1 34 17
Philadelphia Eagles 12 34 17
Cincinnati Bengals 8 33 21
Indianapolis Colts 22 33 21
Jacksonville Jaguars 25 33 21
Miami Dolphins 18 33 21
San Francisco 49ers 32 33 21
Baltimore Ravens 9 31 25
Houston Texans 11 31 25
Los Angeles Rams 23 31 25
New Orleans Saints 31 30 27
Kansas City Chiefs 7 28 28
New York Jets 28 27 29
Cleveland Browns 30 26 30.5
Detroit Lions 13 26 30.5
Oakland Raiders 20 25 32

Table 2: Sacks vs. Baseline Defense Rankings

Correlation: 0.288

Based upon the results, the correlation looks very mediocre.  Are we off track? Well, looking back over the years we have for data, the numbers are really all over the place. Table 3 shows the results going back to 2004:

Year Sack Rank to Pts. Vs. Rank Correlation
2004 0.509
2005 0.393
2006 0.626
2007 0.444
2008 0.435
2009 0.38
2010 0.545
2011 0.177
2012 0.542
2013 0.543
2014 0.061
2015 0.546
2016 0.288

Table 3: Sacks vs. Baseline Defense Rankings 2004-2016

This translates to a wide range of answers, anywhere from a weak correlation (17.7%) between Sacks and Baseline Defensive Ranking to a strong correlation (62.6%). Why would that be the case? The quick answer is that the sack numbers are tightly grouped together. The range of sacks for 26 of the 32 teams is just 28 to 42 sacks, or less than one per game. Results this close together will lead to correlations to other data that are unpredictable and all over the map.

So what is wrong with using sacks anyway? The common misconception is that a sack translates readily to the defense getting the ball back for the offense. The reality is that not all sacks are created equal. While a 15-yard sack on 3rd-and-10 would likely result in a Team Defense getting the ball for the offense, a 1-yard sack on first down is not nearly as valuable. However, in the 1 point for a sack scoring system, there is no differentiation between the two different sacks. It would appear that the sack statistic is misleading, and should be replaced by another one.

TURNING OVER TURNOVERS

Perhaps we should look harder at the other common statistic used in Team Defense scoring, the turnover. Surely one cannot dispute that turnovers relate strongly to team victories. That has to correlate well with Team Defense rankings, right?

Team Pts Vs Rk Takeaways Takeaway Rank
Kansas City Chiefs 7 33 1
Oakland Raiders 20 30 2
Tampa Bay Buccaneers 15 29 3
Arizona Cardinals 14 28 5
Los Angeles Chargers 29 28 5
Baltimore Ravens 9 28 5
Carolina Panthers 26 27 8
Denver Broncos 4 27 8
Minnesota Vikings 6 27 8
Philadelphia Eagles 12 26 10
Green Bay Packers 21 25 12
New York Giants 2 25 12
Miami Dolphins 18 25 12
Pittsburgh Steelers 10 23 14.5
New England Patriots 1 23 14.5
Atlanta Falcons 27 22 16
New Orleans Saints 31 21 17
Washington Redskins 19 20 19.5
Dallas Cowboys 5 20 19.5
Cincinnati Bengals 8 20 19.5
San Francisco 49ers 32 20 19.5
Seattle Seahawks 3 19 22
Tennessee Titans 16.5 18 24
Buffalo Bills 16.5 18 24
Los Angeles Rams 23 18 24
Indianapolis Colts 22 17 26.5
Houston Texans 11 17 26.5
Detroit Lions 13 14 28
Jacksonville Jaguars 25 13 29.5
Cleveland Browns 30 13 29.5
New York Jets 28 12 31
Chicago Bears 24 11 32

Table 4: Turnovers vs. Baseline Defense Rankings

Correlation: 0.299

OK, that is about the same as the previous method (sacks vs. points against).   How can turnovers not significantly contribute to or improve the correlation for a good defensive ranking?

The answer really comes from the mathematics - correlation does not work well with numbers that are close together. From Table 4, you can see most Team Defenses (26 of 32) have from 17 and 30 turnovers, so such a tight grouping will compromise the calculations.

A sanity check is in order - we need to use the common scoring method in its entirety (1 point per sack + 2 points for a turnover) and correlate that result against Average Points (See Table 5):

Team Pts Vs Rk TAs x 2 + Sks TAs x 2 + Sks Rk
Arizona Cardinals 14 104 1
Carolina Panthers 26 101 2
Denver Broncos 4 96 3.5
Tampa Bay Buccaneers 15 96 3.5
Minnesota Vikings 6 95 5
Kansas City Chiefs 7 94 6
Los Angeles Chargers 29 91 7
Green Bay Packers 21 90 8
Baltimore Ravens 9 87 9
Philadelphia Eagles 12 86 10
New York Giants 2 85 11.5
Oakland Raiders 20 85 11.5
Pittsburgh Steelers 10 84 13
Miami Dolphins 18 83 14
Seattle Seahawks 3 80 15.5
New England Patriots 1 80 15.5
Washington Redskins 19 78 17.5
Atlanta Falcons 27 78 17.5
Tennessee Titans 16.5 76 19.5
Dallas Cowboys 5 76 19.5
Buffalo Bills 16.5 75 21
Cincinnati Bengals 8 73 22.5
San Francisco 49ers 32 73 22.5
New Orleans Saints 31 72 24
Indianapolis Colts 22 67 25.5
Los Angeles Rams 23 67 25.5
Houston Texans 11 65 27
Chicago Bears 24 59 28.5
Jacksonville Jaguars 25 59 28.5
Detroit Lions 13 54 30
Cleveland Browns 30 52 31
New York Jets 28 51 32

Table 5: Turnovers and Sacks vs. Baseline Defense Rankings

Correlation: 0.379

This correlation is starting to head back in the right direction.  The correlation between the basic scoring system and Points Against is certainly better than the turnover ranking correlation alone and is closer to the first score with sacks. The combination of both statistics helped in achieving point separation (ranging from 51 to 104 points), but there is definitely room for improvement.

The basic argument against using the sack as a standard measure remains - there is little direct correlation between the sack and elite defenses. Another measure of defense should be considered in place of sacks. However, if sacks are going to be eliminated from the Team Defense scoring system, what will be inserted in its place?

GIVE ME THE $#@!! BALL

Let us reconsider the basic premise of Team Defense. Defenses have two main objectives - keeping the opposition from scoring, and getting the ball back for their offense. We have already seen that the first objective is the baseline measure of Team Defense, so we need to quantify the second criteria to the best of our ability to see if this should be the new fantasy football measure of the performance of a Team Defense.

There are two defensive categories of getting the ball back for the offense that are overlooked in the "turnover" category. Defenses succeed in stopping the opponent by forcing the traditional turnover (fumbles and interceptions) and also by forcing punts and stopping the opponent on fourth down. Our new formula for Team Defense needs to have basis in reality to weigh the value of forced punts and turnovers on downs.

Punts happen numerous times during the game, but they rarely result in the defense giving the offense a short field (under 50 yards from a touchdown). As such, forcing a punt has to be viewed as less opportunistic and less valuable than a fumble or interception, which results in a short field about half of the time. Therefore, our formula begins to look like this:

New Team Defense Score = Turnovers (INTs and Fumbles) x 2 + Forced Punts

Now for the second portion of the new formula - incorporation of turnovers on downs. While this can happen anywhere on the field, it is more likely to occur at both a crucial point in the game and also in a position where the opposing team is in scoring territory. While the resulting field position may not be as good as with a traditional turnover, the impact of both getting the ball for the offense and the likelihood that the 4th down turnover kept the opposition off the scoreboard gives this type of turnover approximately equal value to a fumble or interception. Therefore, we modify the formula to be:

New Team Defense Score = Turnovers (INTs + Fumbles + 4th Down Stops) x 2 + Forced Punts

We label this new equation the "Realistic Team Defense" scoring system. Now all that is left is to test our new formula.

IS THE FANTASY A REALITY

Let us revisit the data from last season once again. Obtaining the two new statistics (4th down turnovers and forced punts), we get the following results:

Team Pts Vs Rk Takeaways 4th Down Stops Forced Punts TOs x 2 + Punts Reality Def Rk
Denver Broncos 4 27 10 89 163 1
Baltimore Ravens 9 28 5 91 157 2
Kansas City Chiefs 7 33 10 69 155 3
Oakland Raiders 20 30 11 72 154 4
New York Giants 2 25 7 89 153 5
Arizona Cardinals 14 28 8 80 152 6
Minnesota Vikings 6 27 11 72 148 7.5
New England Patriots 1 23 11 80 148 7.5
Seattle Seahawks 3 19 14 79 145 9
Miami Dolphins 18 25 7 74 138 10.5
Houston Texans 11 17 10 84 138 10.5
Pittsburgh Steelers 10 23 10 70 136 12.5
Los Angeles Rams 23 18 2 96 136 12.5
Philadelphia Eagles 12 26 10 62 134 14.5
Cincinnati Bengals 8 20 10 74 134 14.5
Carolina Panthers 26 27 4 71 133 16
Tampa Bay Buccaneers 15 29 2 70 132 17
Tennessee Titans 16.5 18 10 72 128 18.5
Los Angeles Chargers 29 28 5 62 128 18.5
Buffalo Bills 16.5 18 10 70 126 20
Atlanta Falcons 27 22 7 66 124 21.5
San Francisco 49ers 32 20 3 78 124 21.5
Jacksonville Jaguars 25 13 7 82 122 23
Green Bay Packers 21 25 6 59 121 24
Dallas Cowboys 5 20 5 70 120 25
Washington Redskins 19 20 7 61 115 26
New York Jets 28 12 8 72 112 27
New Orleans Saints 31 21 6 56 110 28
Indianapolis Colts 22 17 5 63 107 29
Cleveland Browns 30 13 3 74 106 30
Detroit Lions 13 14 5 61 99 31
Chicago Bears 24 11 4 67 97 32

Table 6: All Turnovers and Forced Punts vs. Baseline Defense Rankings

Correlation: 0.633

Definite progress, as this is the best correlation between Points Against Rank so far for 2016. The correlation between the new and improved scoring system and Points Against is over 60% (63.3%), the strongest and the best correlation so far, but how does this compare to prior years?  Table 7 shows the Reality Defense Rank vs. Points Against Rank for the past 13 NFL seasons:

Year Reality Defense Rank to Pts. Vs. Rank Correlation
2004 0.624
2005 0.666
2006 0.688
2007 0.669
2008 0.617
2009 0.649
2010 0.651
2011 0.454
2012 0.635
2013 0.649
2014 0.599
2015 0.706
2015 0.633

Table 7: Reality Defense vs. Baseline Defense Rankings 2004-2016

The addition of all turnovers and punts forced has increased the point separation once again, ranging now from 97 to 163 points (a range of 66 points instead of 53 for all the teams in Table 5). Since 2004, 12 of the 13 NFL regular seasons had 60% or better correlation using Reality Defense scoring.  Only one season, 2011, was significantly below 60% correlation at 45.4%.  Once again, Reality Defense proves itself as the best fantasy metric to use.

So looking at the big picture, 12 of the 13 seasons analyzed had strong correlation - over 60% - to Points Against, one of the best metrics for defense.  The Reality Defense formula emphasizes getting the ball back to the offense by awarding points for not only turnovers but also forced punts and fourth down stops.  These tweaks to the scoring system increases the point range for defenses, allowing the best ones to rise to the top. 

There are additional benefits to this new equation. First, the scores are higher (average score of 9.3 / game) than under the original system (4.9 / game), which goes more towards a better normalization of the Team Defense position on the fantasy roster. By increasing the average score, the net effect is that a Team Defense is now representative of another normalized position player. Table 8 represents the 2016 average score by position of the Top 12 players based upon two common scoring systems:

Pos Non-PPR Pts PPR Pts
QB 22.5 23.2
RB1 13.8 16.4
RB2 7.2 8.9
WR1 12.6 9.0
WR2 7.7 12.2
TE 7.1 11.1
PK 10.0 10.0
Def* 4.9 9.3*

*Based upon the new Realistic Team Defense formula.

Table 8: Average 2016 Fantasy Points / Game for Top 12 Players by Position

Now the Team Defense is comparable to the value of close to a tight end or kicker and just below a Top 24 wide receiver or Top 24 RB (and well below a Top 12 QB). With PPR, the Team Defense declines to a good flex option (RB3, WR3) or an above-average TE2 in value. That would seem to be an appropriate position of value for a strong Team Defense, below a top skill position (QB, RB, WR, TE) but above the lesser valued RB3, WR3, TE2 or kicker position.

One last additional benefit (and variance to the Realistic Team Defense formula) is that the addition of scoring points for a Team Defense scoring play (Touchdown or Safety) allows for the added point value, and also reduces the impact of that event to a lower percentage of the total Team Defense score. Previously, under the original scoring method, teams scored between 51 and 104 points for the season without defensive or special teams touchdowns added (see Table 5). Adding a single touchdown (6 points) varied the overall season score by 5-11%, a large impact. Now with the Realistic Team Defense formula, the range is much larger (97 to 163, see Table 6) so adding a touchdown reduces the impact to 3-6%. This smaller valuation relative to the seasonal performance does seem to be more appropriate.

CONCLUSION

Adoption of the Realistic Team Defense formula for defensive scoring for fantasy leagues going forward would result in a more accurate representation of the value of a Team Defense and better reflect how the actual defensive unit for each team performs in that particular season. The formula incorporates the significant statistics to quantify how well an actual defense performs, and results in a normalized score relative to the skill position players. The variation of adding back in the relatively rare event of a defensive score reduces the impact of the additional points to less of an overall change to the season Team Defense total, and increases the relative value of a Team Defense closer to that of an upper echelon wide receiver.

One last comment – I get asked this question often over the years.  There are several league hosting sites that can support this scoring format, and I suggest that you ask each site whether they can implement these statistics (forced punts, 4th down stops).  I am positive that MyFantasyLeague.com can score defenses this way, for example, but I do not want to steer anyone towards any particular hosting site.

As always, questions, suggestions and comments are always welcome to pasquino@footballguys.com.

DATA SOURCES

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