Are Fantasy Football Defenses Underrated?

Every year, fantasy managers are faced with a decision in the middle to late rounds of drafts: should I draft a 5th running back, a 2nd tight end, or draft my starting fantasy defense? In our Dy-nasty league we are required to keep 15 players from our previous year’s roster, and are faced with a similar decision over whether to keep a back-up position player or a fantasy defense.

Over the past several years, it has become conventional wisdom in the fantasy community to wait to draft your defense and a kicker until the last two rounds in the draft.  The rotoworld and ESPN writers produce countless blurbs and articles on position players, but team defenses barely get a mention. Overall rankings for these sites usually place team defenses near the very end of their lists, if they are even included at all (rotoworld, espn, yahoo).  Ffchamps.com 9th commandment to winning fantasy football is to not draft a kicker of fantasy defense too early, suggesting anything over the last few rounds to be a reach. My sense is most fantasy experts would agree.

(The bottom of Yahoo’s fantasy rankings – Texans and Rams were the 3rd and 4th  defensive teams on their overall ranking list after Seattle (121) and San Fan (145))

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So the question is – are these experts correct? Should managers avoid keeping or drafting these team defenses and just wait until the very end of the draft to select them?

To determine whether fantasy defenses are worth drafting before the last few rounds, we need to answer three questions:
1. Do defenses score meaningful fantasy points for teams?
2. Does the number of seasonal points defenses score vary enough between the defenses or do they all score roughly the same?
3.  Is it possible to predict defense’s future fantasy performance?

Now to answer these questions, I haven’t had the time or resources to conduct the rigorous data analysis that I would want to.  There are several ways to look at these questions and I’m just going to take a quick stab at them. I’d be happy to hear and comments or suggestions.

1. Do defenses score meaningful fantasy points for teams?

In the Dy-nasty Fantasy Football League, fantasy teams averaged a little under 100 points per week. Defenses made up a little under 15% of team’s weekly points, averaging around 12 to 13 points per week.  This approaches or eclipses levels seen in strong RB1s like Adrian Peterson, Eddie Lacy, and Arian Foster and does the same for top wide outs like AJ Green, Dez Bryant, and Brandon Marshall. Clearly these defenses are scoring meaningful points.

2. Does the number of seasonal points defenses score vary enough between the defenses?

This is a slightly more difficult question – do fantasy defenses just score roughly the same amount of points each week?  You often hear this criticism with quarterbacks. While QBs score a lot of points, there are a lot of QBs that score a lot of points, and the conventional wisdom is that there is not enough variability between them to justify drafting them early. We’ll leave whether this criticism is true about QBs for another day, but lets explore the defenses:

Here is the list of the top 15 fantasy defense last year:
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You can see the top 5 defenses (Chiefs through Bills) averaged 14.4 points per game, while the defenses in the 10-15 range (Colts through Raiders – who may often be available on the waiver wire) averaged 11.1 points per game. So we can see that having a good defense netted a team about 3 extra points/week above the replacement waiver wire.

So, how does this compare to other positions? Instead of comparing these defenses to the top position players who we all agree should be drafted first, lets compare them to players who may drafted in the mid to late rounds when you may be considering a top fantasy defense.

For example lets look at tight ends in the 11 to 15 range (Martellus Bennett to Tim Wright). They averaged 5.6 points last year. The guys who we can consider replacement level/waiver wire guys (TEs 21 to 25) scored 4.2 points per game. Suggesting a mid-range TE netted a team about 1.5 extra points/week.

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The same can be said about running backs. A mid/late range running back (51-55) scored about 1 point per week more than a waiver-wire running back (71-76) (4.1 points vs. 3.0 point).

So by drafting a strong defense, teams theoretically gain about three points in their starting line-up, while teams that draft the back-up TE or 5th string RB gain an extra point or so – on their bench!  Now when managers draft these back-ups, many are drafting them more on potential that they blow-up and score considerably more points than the replacement level player. And while that occasionally happens, more often than not it doesn’t and these players are either cut or left on the bench all season. We could argue this point…but regardless, I think we can agree that a 3 point difference per week is meaningful and worth pursing at least in the mid-rounds of the draft if we can meet the last criteria….

3.  Is it possible to predict a defense’s future fantasy performance?

Now this is the big question and often the one you hear most by those recommending to wait on drafting defenses.  The theory is that defensive scoring is too random and we have no idea which defense will score the most points in the upcoming year.  To examine this theory, I attempt a quick and easy evaluation method. Note that there are much better ways to analyze these data but this is just a quick way I thought of without having the hard spreadsheet data.

So, I compared the 2013 Yahoo defense rankings:
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To the actual 2013 results from Yahoo:
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You can see there is some overlap on the list. Seattle is the top team on both list, while the Pats, 49ers, Bengals, Cards, and Rams are all in both top ten lists. So in 2013, Yahoo correctly predicted six of the top ten defenses.  However in 2012, they didn’t perform as well only identifing 4 of 10. Based on the small sample, we can hypothesize that experts are able to predict about five of the top ten teams correctly each year.  If these results were completely random and experts had no predictive ability, we would expect the experts to be only able to name a little under three teams on the top ten list each year. So, while it’s not a great predictive performance, it looks like the results are at least better than chance.   We would need more data to be confident in how much better than chance.

However the fair question would be how well did these yahoo experts do in evaluating another position like RBs. Check out this list, and remember that most of the guys were drafted in the 1st round:
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Five of the top ten running backs were pretty much busts last year – Martin, Spiller, Rice, Foster, Richardson all failed to make it even into the top 25 scoring running backs last year. The other five guys did hit in the top 10, but it’s pretty clear that the predictability of running backs isn’t too strong either.

Also, in case you were wondering, those running backs in the 51-55 range in 2013 that we are considering as a mid/late round fantasy pick were Ronnie Hillman, Roy Helu, Mike Torbert, and Andre Brown – who were largely non-factors last season.

So, while the jury is still out on the value of defensive teams in fantasy drafts, keep this in mind when you’re contemplating whether to draft your 5th running back, 2nd tight end, or fantasy defense.

 

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