Consistency Reports: Defense & Special Teams
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.
After focusing on the IDP side of the game we will round off our defensive review with a look at team defense and special teams. Which defenses could you rely on week-to-week, and who was a liability for fantasy teams?
D/ST Consistency Rankings
|Team||Average||SD||CV||Floor||Ceiling||COR||Total||Top-5||Top 10||Top 12|
Anyone who watched football last season will be able to tell you who topped the list above without looking. The Chicago Bears consistently gave opposing offenses fits, and it translated to fantasy value. They ended the season with a COR ranking over seven points above any other team, and an average points per week nearly two higher than the Rams in second place.
Behind them were some obvious characters, but also some surprises packages. However, there were also some names absent who fantasy owners would have banked on being in the top-10 this time last season. Let’s take a look at the defenses who disappointed and the ones who made for happy owners.
The Overvalued Options
The hype around the Jaguars defense this time last season was immense. The problem was that the hype gave way to them being over drafted last year. The Jaguars were the first defense off the board in the eighth round of drafts on average last season, nine spots ahead of the second place Rams. However, the Jaguars failed to live up to expectations with their performances. Disharmony and poor offensive performances led to this defense struggling to dominate the way they had in 2017.
Last season the Jaguars finished 11th in overall average and 10th when it came to their COR ranking. The good news is that they at least finished as a startable defense across the whole year. The bad news is that they were drafted to be far more than that. Just twice were the Jaguars a top-five unit last year! In fact, just seven times did they finish in the top-12. Hopefully, the Jaguars performance from last year will have taught so fantasy owners a lesson. D/ST performance is hard to predict, and therefore, do not invest too much in them.
The Vikings were another top-three ADP team to struggle last season. The Vikings were just never really fully effective and struggled to string performances together. A lot of the problem was that their offensive line struggled, and their offense failed to string drives together, leaving the defense playing on limited rest on too many occasions. In fact, in 2018 the Vikings defense was on the field the ninth most of any defense in the NFL.
They finished a measly fifth when it came to consistency and 12th in overall scoring. Much like the Jaguars, they ranked in the top-five just twice, and the top-12 on just six occasions. The Vikings defense has not improved massively, but hopefully, the improvements on their offensive line can prevent the defense from needing to be stretched as much as they were last year.
This was all about the injuries for the defending Super Bowl champions. Their offense did a good job limiting their exposure, as they saw the fourth least time on the field defensively. However, the back end was absolutely hammered with injuries and they just could not repeat the performance of 2017. Their 2017 performance was driven thanks to a number of opportunistic plays, and that is hard to repeat, but the injuries did not help.
In 2018 the Eagles ranks 25th in weekly average and 20th in COR, finishing as a top-12 defense just four times. The lesson here is once again about over-investing in defenses. D/ST performances can be so volatile year-to-year, especially if your performances were built on interceptions and touchdowns. The Eagles dreadful season had a lot to do with injuries, but even with a fully healthy they would have been hard-pressed to match what they did in 2017.
The Surprise packages
This is exactly what many expected last season, yet the Bears were drafted 10th among D/STs in 2018. Likely the reason for this performance difference is that Khalil Mack was traded relatively late in the offseason. To be precise that trade happened September 2nd, just a week before the NFL season began. That trade turned a mid-level defense into one of the best in the league.
All told they finished top-five six times and top-12 on 10 occasions. Unfortunately, trying to predict which team might make a trade that takes them from good to elite is not an exact science. One other caveat with this team is that they did benefit from some opportunistic plays, which we have seen are hard to repeat year-to-year. The Bears should be the first defense taken this season, but learn from the Jaguars last season, and do not take them ridiculously early. It simply is not worth it.
This one is fascinating because honestly, I am not sure what the Titans did to make it happen. Bringing in defensive-minded head coach Mike Vrabel will certainly have helped. This team finished joint fifth in the consistency rankings because simply they just did what they had to every week. They were solid for the most part on all three levels and their defense carried them as far as it did. Next season they should see improved offenses in their division, which will make this tough. However, they have a young defense, and they should continue to run a ball control offense. This defense is my sleeper to finish top-three next season, and they are largely going undrafted right now.
Kansas City Chiefs
I wanted to use this opportunity to highlight that on-field performances can be deceiving. If you watched the Chiefs last year they looked to be shredded by opposing offenses on a regular basis. However, they had a lot of opportunities to be opportunistic, which led them to a fifth-place finish in weekly average and seventh in consistency rankings. This is all about having an offense which constantly put opponents under pressure. When you have Patrick Mahomes and company racking up points, then opposing offenses have to take more chances and offer more opportunities for sacks and interceptions.
Why this is important is because many believe the Chiefs offense will be good again in 2019. If that is the case then there is the reason to have optimism in the Chiefs defense repeating this level of consistency in 2018. Combine that with the additions they made to their team this offseason and they could go one step better this season.
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.