Player Value Gap Assessment

July 29, 2015
By

(This article was first published on Fantasy Football Analytics » R | Fantasy Football Analytics, and kindly contributed to R-bloggers)

Looking at fantasy football projections we have a group of experts providing their views on how a player will do during the football season. We have collected projections from several sources and are able to analyze them in detail.

Football is a balanced game in the sense that all passing yards should be matched by receiving yards, passing touchdowns should match receiving touchdowns, and pass completions should match pass receptions. What information can the projections offer us about value gaps if we examine these stat categories? If a team’s passing yards is projected to be higher than the receiving yards, then you can ask yourself: are the QB passing yards higher than they should be or are the receivers’ reception yards lower than they should be? In any case it may provide some room to explore some value gaps. Using historical data we can look at the accuracy of these stat categories and see if either of these are under- or over-estimated.

Passing and receiving yards

Let’s take a look at the data for the 2015 season. We have data from 15 different sources and if we add up all the passing yards projected for the QBs for a team and compare those to the sum of projected receiving yards for RBs, WRs, and TEs the picture below emerges:

passYdsDifference

At one end we have New Orleans with on average 453 passing yards more than receiving yards; at the other end is Chicago with on average 314 passing yards less than receiving yards. If we take the two data points at each end we could argue two different things for each:

  • Drew Brees is over-rated. In a standard league setup with 1 point per 25 yards we are looking at taking about 18 points off his projections.
  • His receivers are under-rated. Brandin Cooks accounts for about 22% of the projected reception yards, so to get his share of the gap he would have almost 100 yards more which would translate into another 10 points for him.
  • Jay Cutler is under-rated. If Jay Culter can pass for another 314 yards his point projections are about 12 points short. Now you could argue that Jay Culter could be benched hallway through the season, but the number represents the team total of passing yards so it includes all QBs on the team.
  • Again, if Jay Cutler is not under-rated then his receivers are over-rated. Alshon Jeffrey accounts for about 27% of the projected receiving yards so he could take an 85 yard hit on the projections or about 8–9 points.

In general it looks like there is a tendency to project passing yards to be less than receiving yards, since there are more teams with more passing yards than the other way around. However, projected passing yards are only about 34 yards more than projected receiving yards, on average.

Passing and receiving touchdowns

Touchdowns should also be balanced out so passing touchdowns are equal to receiving touchdowns, but as the graph below shows, passing touchdowns are projected to be higher than receiving touchdowns.

passTdDifference

Again New Orleans is to be found on the higher end with 4.57 more passing touchdowns than receiving touchdowns, only surpassed by Denver with 4.60 more passing touchdowns than receiving touchdowns. If a standard 4 points is awarded for passing touchdowns then Drew Brees’s projections could be inflated by another 18 points which along with the 18 points from above then puts him at risk to lose 36 points total. That could mean a significant drop in positional ranking.

On the receiver side for New Orleans, Brandin Cooks accounts for about 20% of the projected receiving touchdowns, so he could see an extra touchdown which could put him up another 6 points or a total of 16 points if you count the receiving yards as well.

Pass completions and receptions

The final indicator on value gaps comes from comparing pass completions to pass receptions. The general picture here is that pass completions here are always projected lower than pass receptions, but in this case New Orleans is pretty balanced with just 2 more pass receptions than completions.

passCompDifference

This set of data makes the assessment complete in the sense that you will have to look at the three stats to see what value gaps there may be. For New Orleans the number of completed passes almost matches the number of receptions by offensive players, but passing yards and touchdowns are higher than receiving yards and touchdowns. So yards per completion is too high for Drew Brees and/or yards per completion is too low for his receivers. This is where you can try and make an assessment for yourself. If you think it is a little bit of both then you can split the 453 yards and take some away from Brees and give it to the receivers. Same thing for the touchdowns – maybe split them 50/50 and take 2 away from Brees and give 2 to the receivers.

Conclusion

Although experts work hard to provide projections for football players, they do not always match up when looking at the data at the team level. For the 2015 projected stats we have seen that:

  • Receiving yards are mostly projected higher than passing yards, but on average by only about 34 yards
  • Passing touchdowns are almost always projected higher than receiving touchdowns, on average 1.5 passing touchdowns more than receiving touchdowns
  • Pass completions are always projected lower than pass receptions, on average 21.4 completions more than receptions

Looking at the individual teams you can explore these differences to find potential value gaps. However there is not a definite solution to close the value gap. Historical data can provide some insight into the accuracy of the stats and give an indication on the direction to take on closing this gap. If we go back and look at the data from 2008 through 2014 we find that both receiving and passing yards were over-estimated over that time period, receiving yards by 387 yards on average and passing yards by 283 yards on average compared to the actual values. So passing yards are slightly more accurate than receiving yards but both projections should likely be adjusted downward some. Projected passing and receiving touchdowns seem historically pretty accurate. In the time period from 2008 to 2014, both projected passing and receiving touchdowns are only a couple of touchdowns over the actual values. On the other hand, pass receptions and pass completions were both under-estimated in the same time period. Projected pass completions were on average 42 completions under the actual number of completions and pass receptions were on average 33 receptions under the actual number of receptions. Overall it seems that projected passing data is more accurate than receiving data and could point us to making larger adjustments of receiving projections than passing projections. So in reference to Drew Brees: looking at the historical data in general it does not provide a clear way of resolving the value gap, but for this season it could look like it is more likely that Brees is over-rated than it is that his wide receivers are under-rated. We will be dissecting the historical accuracy of the data in future posts, so stay tuned for that.

You can find the R script used for the analysis above here: https://github.com/dadrivr/FantasyFootballAnalyticsR/tree/master/R%20Scripts/Posts/Value%20Gap%20analysis/R%20Scripts

The post Player Value Gap Assessment appeared first on Fantasy Football Analytics.

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