Daily Fantasy Football: What to Look for When Selecting Your Defense

What can past results tell us about pinpointing top performers on a weekly basis?

Like in season-long fantasy leagues, kickers and defense/special teams (D/ST) units have been the least valued commodities in daily fantasy football. Not only are they not as exciting to follow, but they're cheap, carry capped ceilings and -- maybe most of all -- unpredictable.

For the 2018 NFL season, FanDuel has done DFS players a solid by abolishing the highly volatile (and long hated) kicker position. We still have the D/ST slot to deal with, but is it really all that unpredictable?

Let's take a look into the data to see what trends have developed among top defensive performances and how they could aid in your weekly selection process.

Where Do Defenses' Points Come From?

Thanks to FantasyData, I was able to pull weekly D/ST scoring for each week of the 2016 and 2017 seasons. All total, we have 1,024 data entries to work with, and each performance is accompanied by team stats, opposing offense and salary.

Using the team scoring stats and FanDuel's standard scoring rules, I was able to calculate the percentage of D/ST FanDuel points by category. "Other" includes punt or kick blocks and extra point returns, which were not available in the data.

Here's the breakdown:

D/ST - Percentage of FanDuel Points

If it wasn't already obvious, sacks and interceptions make up more than 50% of defense and special teams' FanDuel points. And when we include fumble recoveries, we get exactly 70.9% of the scoring. Only 4.7% is spread across the "other" category while special teams touchdown returns (3.4%) and defensive safeties (1.0%) come in as the least significant categories over the last two seasons.

But, while it's good to know the lay of the land before climbing to the top, we're concerned with what it takes to be -- or, for our purposes, to find -- the highest-scoring defense of a single week. With that goal in mind, I narrowed down the sample to those teams with the most FanDuel points in a given week, including ties, to get a sample of 38.

Within that sample, the distribution of points shifts significantly.

Percentage of FanDuel PointsOverallTop PerformersDifference
Fumble Recoveries15.4%11.2%-4.2%
Defensive Touchdowns11.3%27.7%16.4%
Return Touchdowns3.4%2.9%-0.5%
Points Allowed8.8%18.4%9.6%

Defensive touchdowns -- while volatile -- appear to be king for most top-performing defenses. Points allowed have also played a larger role, with sacks taking the most substantial hit, while interceptions and forced fumbles drop marginally.

Furthermore, when we look at the 38 weekly-high performances, 27 of them included a defensive touchdown, with 10 of them boasting at least 2 such scores.

And if we zero in on the points allowed category, we see that 4 games ended in shutouts for the top defense while 14 others held the opposing offense to single-digit points. Only five of those performances came when the defense surrendered 20-plus points, including two instances (once in each year) in which a defensive unit was awarded -4 FanDuel points for allowing 35-plus points in the game.

What About Matchups?

Now, let's look a little closer at the caliber of defenses and opposing offenses to see how that's played a role in defensive production in fantasy.

Using our Net Expected Points (NEP) metric, which measures a player or team's points added given historical down-and-distance data, we can evaluate each side of the matchup by their end-of-season rank in total adjusted NEP.

Broken down into four quarters (top eight and so on), here's the distribution.

NEP Rank Defense Opposing Offense
1-8 16 2
9-16 14 12
17-24 7 13
25-32 1 11

The average rank of the defenses and offenses are 11th and 20th, respectively.

Digging into these on a smaller scale, it's worth noting that our top-ranked defenses in 2016 (the Denver Broncos) and 2017 (the Jacksonville Jaguars) have combined for four weeks with top honors (two by each). Impressively enough, one of the Jaguars' top weeks came against the NFL's second-best offense -- the Pittsburgh Steelers -- in Week 5 of this season, when Ben Roethlisberger threw five picks, two of which went for pick-sixes.

Eight other performances came via top-five defensive units. For these top-five defenses (including the Broncos and Jags), their opponents' offense was, on average, 18th in the NFL. There was no other top-five offense, and eight offenses ranked 17th or worse. Naturally, 44.8% of their FanDuel points have come from points allowed, with a lower percentage (26.7%) from defensive scores.

However, it is interesting to see nearly as many outstanding defensive performances from those ranked 9th to 16th as those in the top 8. Combined, those 14 opposing offenses had an average rank of 18th, as well, with 9 of them 15th or worse and one in the top 10.

Targeting bottom-tier defenses hasn't been the worst idea, though. Of the eight performances from those units ranked 17th to 32nd, the best opposing offense was last year's Green Bay Packers, who ranked 13th and at the time had a healthy Aaron Rodgers. Outside of that, the average offense ranked 30th, with three of them dead last and two others ranked 31st. Their reliance has primarily been on defensive touchdowns (30.4%) and sacks (20.9%) as points allowed (13.3%) have been less important for the performances of these squads.

In summary, the best defenses can perform well against any offense, but it's more likely that they'll be better as they take advantage of middling to below-average offenses. The middle tier of defenses are also better targets against bottom-half offenses, but as you dig into the bottom defenses, they rely heavily on soft matchups, which confirms a common approach to DFS defenses.

Knowing what we know now, as an example, which D/ST units make for the ideal Week 1 target to open the 2018 season?

If you are are opting for a top-tier defense, both the Jaguars ($4,700) at the New York Giants and Minnesota Vikings ($4,500) against the San Francisco 49ers fit the mold. Their defenses rank third and first, respectively, in our power rankings, and in our DFS projections, the two are first and second in points allowed, and both units are in the top-three in terms of projected defensive touchdowns. Their opponents' offenses are 21st and 9th heading into the season, though the higher-ranked Niners will be on the road in the tough U.S. Bank Stadium.

At just $4,000, Washington might be the mid-level defense to pay down for in a road matchup with the Arizona Cardinals. Their defense rates 14th and the Cardinals' offense -- thanks to a bottom-three offensive line -- sits 29th. It's a recipe for success, and our models agree, projecting Washington for the fifth-fewest points allowed and as the defense most likely to notch a defensive score.

So, if you still think selecting your defense is an inexact science, you're not completely wrong there. But the data points to some trends worth exploiting as we head into the 2018 daily fantasy football season.