Feature update: wARP

tl;dr

wARP: weighted average running position. It's live now. You can see it where you'd expect to see it: the main stats page, the driver page, and race page.

Why?

Average running position gives equal credit to every lap in a race. That's good, because it gives a driver credit for their whole race, but it dismisses the relative predictability of the individual laps.

We've seen with PFAE that starting position – the earliest lap – heavily discounts average finish toward mid-pack. These are the average finishes of each of the top ten starting positions in the Cup series. Starting first doesn't even average a top ten finish!

Start	Races	Wins	AFP	Avg Gain
1	270	34	11.87	-10.87
2	270	25	12.08	-10.08
3	270	21	12.95	-9.95
4	270	24	12.18	-8.18
5	270	17	13.83	-8.83
6	270	13	15.18	-9.18
7	270	4	13.71	-6.71
8	270	18	14.31	-6.31
9	270	17	14.46	-5.46
10	270	10	14.81	-4.81

We can see a similar phenomenon when we look at the average finish of individual running positions over the course of the race. Here's a few selected running position charts:

You can see that early early laps don't correlate very strongly with the finish. At the end of the first stage – usually about a quarter of the way into the race – the driver in first place averages a tenth place finish. Even at the halfway point, they'll still only average a ninth place finish. But as the race gets later and later, that average finish converges with the running position. That makes sense, of course, as there's less time to gain and lose position as the race goes on. Once you cross the halfway point, there are no more guaranteed pitstops, so it's critical for drivers to get into forward positions when it matters.

Weighted average running position asks how good a driver is at getting into those forward positions. It weighs laps according to the graphs above: how far away the point on the graph is from the selected running position..