Feature update: Weighted Success Rate (wSucc%) and PFAEz

Weighted Success Rate, or wSucc%, and PFAEz are live now.

Unweighted success rate and PFAE both compare the driver's result with the recent historical average finish of drivers starting from a similar position. Drivers starting third have historically averaged a 14.7 finish. If our driver finishes sixth, that's 8.7 positions above expected and a successful race, despite dropping three spots.

The new metrics use the full distribution. Weighted success rate would say that the sixth-place result is a 65th-percentile finish for a driver starting third, and give the driver a score of 65%.

PFAEz is the PFAE z-score. Normal PFAE says how many positions above or below the average a driver finished. PFAEz says whether that difference was small or large compared with other races from that starting position. Zero means the historical average. Positive scores are better than expected and negative scores are worse. The majority of drivers will sit between 1 and -1; beyond that are exceptional results.

These metrics do a better job of crediting drivers for exceptional jobs, at the cost of being a bit more complicated. Success rate and PFAE remain excellent intuitive stats.

You can find both new metrics on the Advanced driver reports for Cup, O’Reilly and Trucks.

Here are the leaders through July 26: