IDP Consistency Reports: Defensive Backs
The question of valuing players is the seemingly never-ending issue when it comes to fantasy football. Should you target a player with upside, or should it be someone who might have a lower ceiling but provides you with consistency week to week? What about if you had a way to combine both elements in one ranking? Well, here at FFStatistics, we have attempted to do just that with our Consistency Rating (COR). COR is created by taking a player’s calculated ceiling and dividing it by their coefficient of variation (more information on these and the math behind them at the bottom of the article).
Using COR, we can get an easy snapshot of where players rank weekly. We can also compare their COR value to their average fantasy points total. By looking at the difference between the two values, we can identify various subsets of players. Some players posted an average that looked great but using COR we can find out whether they were reliable or not on a week-to-week basis. The same goes for players who posted average points totals, which were not significant. Some did it and were wildly inconsistent, and others were pretty reliable.
In this next set of articles, we are going to switch our focus to the IDP side of things. However, instead of focusing on surprise names, we are going to look at the overall picture in greater detail than we did with the offensive side of the ball. We will be looking at which positions are the most reliable IDP contributors. We will also look at what made some players stood out among the crowd last season. This first article will look at the defensive backs.
The Scoring System
More than the offensive side of the ball, the scoring system for IDP makes a massive difference to players values. Depending on which plays are emphasized by the scoring system, it will alter the importance of individual players. If interceptions are a premium scorer, then defensive backs see a boost. If sacks or tackles for loss get boosted, then the emphasis leans more to the defensive line.
For this article, I will be using a scoring system often seen as standard in IDP fantasy football. The scoring is as follows:
- 1.5 per solo tackle
- 0.5 per assisted tackle
- 2 per forced fumble
- 2 per fumble recovery
- 4 per sack
- 4 per interception
- 6 per touchdown
- 1 per pass deflected
Defensive Back COR Rankings
|John Johnson III||LA||167.5||10.47||3.64||0.35||6.82||14.11||40.54|
|Ha Ha Clinton-Dix||WAS||151||9.44||3.45||0.37||5.99||12.89||35.26|
|Jessie Bates III||CIN||157.5||9.84||4.11||0.42||5.74||13.95||33.44|
|Earl Thomas III||SEA||51.5||10.3||5.22||0.51||5.08||15.52||30.64|
|Kenny Moore II||IND||141||8.81||3.91||0.44||4.9||12.72||28.67|
|Chris Harris Jr.||DEN||100.5||8.38||5.12||0.61||3.25||13.5||22.07|
|D.J. Swearinger Sr.||ARZ||104||7.43||4.84||0.65||2.59||12.27||18.83|
There will be some unsurprising names to many in the top-10 with the appearances of Jamal Adams, Derwin James, and Landon Collins. Quinton Dunbar is the most obviously interesting name. For one he is the highest cornerback on the COR list, but also his value may be slightly over-inflated by his relative lack of playing time. In total last season, he appeared in six games over 12 games, before being placed on the injured reserve to end the season. When he was on the field he produced between 7-and-14 fantasy points. That is definitely a positive, and it will be interesting to see if he can repeat that when healthy.
Cornerback vs. Safety
For this article, cornerbacks and safeties are grouped together as a generic defensive back position. A lot of fantasy sites combine the two for the purposes of their game and therefore we have done that here. However, it is still worth dissecting how the consistency plays out between the two positions.
We already spoke about Dunbar being in the top-five, but he is the only cornerback to have achieved that level of consistency. If we extend that to the top-10 then bring in a second cornerback, in Chidobe Awuzie (10th). In fact, the ratio of one corner for every four safeties holds true through the top-20. Logan Ryan is the only corner in the 10-15 range, with Trumaine Johnson finding himself the sole cornerback in the 15-20 range.
Generally, as you look down the list you will find the list dominated by safeties. The cornerback position is in many ways more glamorous, but for fantasy, it is the safeties that get the opportunity to provide consistent numbers. The reason for that is generally due to their advantage in tackles. Part of their job more so than cornerbacks is to come up and support the run defense. That gives them the chance to put up consistent stats week-to-week.
Why Did Those Cornerbacks Stand Out?
Dunbar was a general stand out because he just took advantage of increased opportunity. He may have only played seven games but he started in a career-high six of those. That allowed him to be involved in 39 tackles, another career high for a single season, but more importantly, he made those tackles consistently in his games.
Awusie is another player who benefitted from extended playing time. He was again simply a consistent tackler and as a second-year player, someone that opponents tried to target. Same goes for Logan Ryan, who was the number two cornerback to Malcolm Butler in Tennessee. That meant that teams were looking his way plenty. As with all IDP corner value is about the opportunity. Often the biggest names at the cornerback position are not the most consistent contributors. When they are targetted, they can give handsome returns. However, teams tend to not go after them as often as the secondary guys. For that reason, IDP value can often be found in the talented second cornerbacks on teams.
Defensive Backs Overall
This is a somewhat similar story to the cornerback against safety debate. Overall in the COR rankings, there was one defensive back in the top-five, three in the top-10, six in the top-15, nine in top-20 and 18 in the top-50. The fact that safeties get the chance to make semi-regular tackles in games, helps make the position overall consistent. For reference, those four cornerbacks in the top-20 of the defensive back COR rankings were the only ones in the top-50 overall.
When you go into your IDP drafts this season it is dangerous to ignore the effect of defensive backs, as just simply random providers. Good safeties will provide you with consistency, making them well worth investing in at a reasonable value. Often defensive backs can be left to slide down IDP drafts, as owners do not trust the level of consistency they provide. However, we can see above that if that happens in your league, then it is possible to take advantage of value among certain names.
The Math Behind the Stats
For those of you interested here is how all of the numbers that make up the consistency rating (COR) are produced. I am going to go full geek mode here so I fully understand if you just want to bypass this section and take my word for it!
Standard Deviation and Coefficient of Variation
First, we need to look at the average and standard deviation for that player. The standard deviation quantifies how spread out the numbers are. However, raw standard deviation numbers are messy to look at and hard to take in. They are also biased by the average of the player. A player with a lower average will have a bigger change in standard deviation for smaller relative changes in fantasy points than a player with a larger average weekly score. Therefore, we use another factor called the coefficient of variation (C.V.). C.V. takes the standard deviation and divides it by the average, allowing you to compare two players side by side regardless of their weekly average.
There is a downside of using C.V. If a player is consistently bad he will have a low C.V. and rank highly if we simply ranked players by that metric. Therefore, we need to look at a way to incorporate a players weekly points total. To do this we can calculate a players floor and ceiling, using their average and standard deviation. Over time the fantasy points scored by a player follow a normal distribution. With normal distribution we see the percentage of observations fall within one, two, or three standard deviations either side of the mean.
68% of the observations will fall within one standard deviation either side of the mean. 95% within two standard deviations and 99.7% within three standard deviations. The wider we go with the standard deviations the harder it is to accurately predict a player. Therefore, the floors and ceilings are calculated by looking at the values which fall one standard deviation either side of a players weekly average.
Finally, the COR itself. COR is calculated by taking a player’s calculated ceiling and dividing it by the C.V. The higher the number the better that player ranks as a risk/reward play for fantasy owners. COR gives weight to players who have a high ceiling, but also to those who are consistent. Players who consistently put up big points totals rank highly and players who are highly variable fall further down the rankings.