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Regression Alert: A Temporary Reprieve

Beginning to close the books as the season winds down.

Welcome to Regression Alert, your weekly guide to using regression to predict the future with uncanny accuracy.

The Scorecard

Returning readers, you know how this works by now, but for new readers here's the deal. Every week I take a look at a specific statistic that is prone to regression and identify high and low outliers in that statistic, and then I wave my hands in the air and shout “regression!”

But since predictions aren't any fun without someone holding your feet to the fire afterward, I don't stop there. I lump all of the high outliers into Group A. I lump all of the low outliers into Group B. I verify that Group A is outperforming Group B. And then I predict that Group B will outperform Group A over the next four weeks.

I don't get to pick and choose my groups, beyond being free to pick and choose what statistics are especially prone to regression. If I'm tracking yards per target, and Antonio Brown is one of the high outliers in yards per target, then Antonio Brown goes into Group A and may the fantasy gods show mercy on my predictions.

And then, groups chosen and predictions made, I track my progress. That's this.

In Week 2, I outlined what regression was, what it wasn't, and how it worked. No prediction was made.

In Week 3, I listed running backs with exceptionally high and low yards per carry averages and predicted that the low-ypc cohort would outperform the high-ypc cohort over the next four weeks.

In Week 4, I looked at receivers who were overperforming and underperforming in yards per target and predicted that the underperformers would outperform the overperformers over the next four weeks.

In Week 5, I compared the predictive accuracy of in-season results to the predictive accuracy of preseason ADP. Outside of a general prediction that players would tend to regress in the direction of their preseason ADP, no specific prediction was made.

In Week 6, I looked at quarterbacks who were throwing too many or too few touchdowns given the amount of passing yards they were accumulating, then predicted that the underperformers would score more fantasy points than the overperformers going forward.

In Week 7, I looked at receivers who were catching too many or too few touchdowns based on their yardage total, then predicted that the underperformers would score more fantasy points than the overperformers going forward.

In Week 8, I revisited yards per carry, again predicting that the high-carry, low-ypc group would outrush the low-carry, high-ypc group going forward.

In Week 9, I went back to yard to touchdown ratios, predicting that the low-touchdown group would close the gap substantially with the high-touchdown group going forward.

In Week 10, I discussed the pitfalls of predicting regression over 4-week windows. No specific prediction was made.

In Week 11, I once more delved into the theory behind regression and highlighted the importance of not cherrypicking which players are “too good” or “not good enough” to regress.

In Week 12, I took one more shot at touchdown regression for quarterbacks, predicting that the low-touchdown cohort would close the gap with the high-touchdown cohort going forward.

In Week 13, I decided to close the predictions out with a bang, sorting the top 100 skill position players in yards per touchdown ratio and predicting that the third with the fewest touchdowns would outperform the third with the most touchdowns going forward.

In Week 14, I delved into Alvin Kamara's aberrant touchdown rate, whether sometimes outliers were actually indicators, and whether anyone could possibly be “regression-proof”.

Statistic for regressionPerformance before predictionPerformance since predictionWeeks remaining
yards per carry Group A had 60% more rushing yards per game Group B has 16% more rushing yards per game None (Win!)
yards per target Group A had 16% more receiving yards per game Group B has 11% more receiving yards per game None (Win!)
passing yards per touchdown Group A had 13% more fantasy points per game Group A has 17% more fantasy points per game None (Loss)
receiving yards per touchdown Group A had 28% more fantasy points per game Group B has 1% more fantasy points per game None (Win!)
yards per carry Group A had 25% more fantasy points per game Group B has 16% more fantasy points per game None (Win!)
rushing yards per touchdown Group A had 21% more fantasy points per game Group B has 8% more fantasy points per game None (Win!)
passing yards per touchdown Group A had 14% more fantasy points per game Group A has 47% more fantasy points per game 1
yards from scrimmage per touchdown Group A had 7% more fantasy points per game Group B has 19% more fantasy points per game 2

It seems the universe can't stop dropping hints about how terrible of an idea it was to predict quarterback regression this season. As if our high-touchdown quarterbacks weren't doing well enough, Wentz and Prescott were both top-3 passers last week, and Wentz's torn ACL means there'll be no chance for regression to settle in this year; his 2017 is now cemented as one of the highest touchdown rates in league history.

On the opposite side of the ledger, the universe laughed at my puny attempts to predict improvement, dumping one of the largest blizzards in years on poor Jacoby Brissett while news came out that Marcus Mariota has been playing on an ankle injury that will likely require surgery after the season.

So let's just go ahead and take the loss at quarterback once again and console ourselves that at least every other position has been regression as usual.

Now on to the analysis... sort of.

A Temporary Reprieve

We're kind of at a weird point of the season right now. It's too late to make and track any new predictions, but it's also too early to do much in the way of season-long analysis.

Over the next two weeks, I plan on doing a deep dive into what went wrong at quarterback, as well as a year-long retrospective on regression as a whole. But for the former, I wanted to wait until my last quarterback prediction was officially final, and for the latter I kind of need the whole year to be done before retrospectivizing it.

So consider this week a brief reprieve from the constant cries of unsustainability. Best of luck to everyone still alive in their fantasy playoffs, and if your quarterback is Dak Prescott, may he continue to laugh in the face of regression, (and also hopefully avoid an ACL tear).