Using Coefficient of Variation and Consistency to Help with Weekly Decisions

Peter Howard

Keeping track of week to week changes in volume and opportunity is useful for starts, sits and other weekly decisions. It’s a tedious task but one that can yield big results. In some ways monitoring fantasy output is a way of combining a volume metrics. Volume is valuable because it can lead to production and is consistent, but consistent production is also an indicator of volume.

One way of monitoring consistency is the coefficient of variation, or CV (a way to measure the variation in a sample of data). It is calculated by dividing the standard deviation by the mean. In short, we can use it to compare how much variation there is in a series of numbers in a data sample. We can apply this in a number of ways for fantasy. This season I’ve been using it to measure the consistency of player’s fantasy point production, in points per receptions (PPR) formats. It is most useful when combined with other context and statistics.

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As with anything in fantasy football, we have to remember that football is variation, or randomness, personified. Everything from the interconnectedness of the play of individual players to the necessarily small sample size’ means that stats and metrics can only tell us so much without context, skill and analysis. This makes consistency both hard to trust but also deeply valuable.

No one benefits from knowing that a player with zero fantasy points every week is consistent, after all. I don’t want to draw a hard and fast line on what a good or bad CV % is, but to begin with you can think of anything 30% or below as excellent. Few wide receivers will post this level of consistency on a whole season. Jarvis Landry, for example, leads the league at his position in CV and he currently has a CV of just over 31%. He also ranks 14th over the last four weeks. I keep all the samples to 8 Points Per Game (PPG) to keep it only fantasy relevant players.

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*Top twelve WR Consistency for the whole season so far in 2017)

Here are the top twelve running backs in CV for the entire 2017 season so far for comparison.

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We can also use CV to try and pinpoint more recent trends to gain an edge. Here are the top 22 wide receivers in consistency over the last four weeks of the 2017 NFL season.

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*Top 22 WR Consistency last four weeks (minimum three weeks of results)

I’ve highlighted the top six players in PPG as well. While Amari Cooper’s CV is at the top, and that’s good, the fact is he has been consistently posting ten PPG, is “less good.” Clearly players posting 15-plus PPG have a much higher and floor and are better targets when looking for consistency.

I’ve also included the players’ target volume for the last three weeks. The last two columns contain their Week 12 opponent and 4for4.com’s adjusted Fantasy Points Allowed matchups rating (the higher the number, the better the matchup). Hopefully this all provides some provides context for week 12 decisions.

Take Aways

Adam Thielen, WR MIN

As you should expect by this point, Adam Thielen ranks at the top of the list in my interpretation. He is the top three in consistency over the last four weeks (23.5% CV) and yet is the only player in the top 22 to average over 25 fantasy points per game. Simply put, there has been no better start than Adam Thielen as a week-in week-out starter. He ranks 13th on the entire season in CV.

Michael Thomas, WR NO

This is a name I expected on the list but expected it to be even higher. While a 26.3% CV is nothing to sneeze at, nor his 17 PPG average, I think he is disproportionately the more valued wide receiver in the top 12 in CV. He is either less consistent or has a lower in PPG then the three player other players on this list.

However, he and Adam Thielen are clearly the most likely to sustain this type of production across the season. What’s more, and this is impressive, Thomas is the only WR in the top 12 over the last four weeks and in the top five for the entire season. Frankly, that is mind-blowing consistency with this healthy PPG.

Roby Anderson, WR NYJ

Fellow DLF writer Bobby Koch recently wrote about how we may be undervaluing Robby Anderson in Dynasty and this does nothing to cool that fire. Robby Anderson is the only player in the last four weeks with below 30% CV to post greater than 18 fantasy points per game (19.6) (so, the highest PPG other than Thielen). Simply put, in the last four weeks, Anderson has been the second best starting wide receiver week in and week out since week eight. He ranks 22nd on the entire season in CV.

Demaryius Thomas, WR DEN

This was a surprise given the relative disappointment he has been on the season at large. His recent volume of targets (29 in three weeks!) helps explain it however. I don’t know if the volume will continue should Brock Osweiler be replaced. But for the last four weeks, at least, Demaryius Thomas has posted a 24% CV (eye popping) and an average of 16.4 PPG. He ranks 17th on the entire season.

Outside of drastic offensive changes, I think all four of these players have to be locked in starters right now.

Hope it helps

I’m going to keep tracking CV this season and beyond, as well as measuring the value it holds to weekly decisions. I hope for now it will provide some context for boom or bust starts and an X-factor for your weekly decisions. The playoffs will be upon us soon enough and very edge counts, after all.

I post all stats and metrics I track weekly, including CV for all positions, so feel free to check them out on Twitter (@pahowdy). I’d also appreciate any comments on what you find useful or might find more useful to track and post.

Good luck in week 12.

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peter howard
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