DVOA — robbygreer.com - NFL Analytics Research

Weighted EPA Methodology & Performance

Summary

WEPA is a framework that weights EPA to improve its predictive power
The goal of WEPA is to use publicly available play-by-play data to create an open source model that is free, reproducible, and more predictive than proprietary alternatives
The 2018 WEPA proof-of-concept suffered from overfitting and used forward looking data to train, resulting in an unreliable model
This post addresses these issues while improving the model through an expanded dataset and feature group
The new WEPA model is substantially more reliable and predicts future point margin better than current proprietary alternatives

Analytics, OpinionRobbySeptember 5, 2020EPA, Weighted EPA, DVOA, Prediction, Point Margin, NFLComment

What's the Best NFL Game Grade?

Final scores are reasonable predictors of future performance, but game grades like DVOA and WEPA are measurably better
Individually, WEPA was the best game grade tested, beating both DVOA and PFF in descriptive and predictive power
Even when a game grade isn’t as predictive of future performance as other game grades, incorporating it into a blended game grade yields a metric that is more predictive than any individual game grade
Depending on implementation, a game grade that blends Point Differential, WEPA, and PFF tends to perform best

AnalyticsRobbyDecember 26, 2019NFL, Game Grades, WEPA, DVOA, PFFComment

Weighting EPA to Improve Prediction

By weighting certain play types, Expected Points Added (EPA) can be made more accurate than Point Margin in predicting out of sample Point Margin. Even without controlling for strength of schedule, homefield, or any pre-season priors, a weighted EPA can even be more accurate than DVOA, which includes all of the aforementioned data points.