NASCAR provides lots of statistics, but beware: the numbers can be deceiving. That’s especially true for laps led and lead changes
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Laps Led
The box score for each race always includes statistics like how many drivers led, how many laps each led, and how many lead changes took place. Let’s use last week’s Talladega race as an example. As always, thanks to racing-reference.info for the data.
The box score shows 58 lead changes and 18 drivers who led one or more laps. But let’s delve a little deeper.
Simplest Case: Laps Led
Here’s are the numbers of laps each driver led
Right away, you can see that claiming 18 distinct leaders is a little disingenuous, because 7 of those 18 led two laps or fewer. But, you might say, leading a lap is leading a lap. Everyone should get credit, even if they only led one.
But there’s a difference between taking the lead during a green-flag run and staying out during a caution. I’ve shown previously that the number of cautions directly influences the number of lead changes
Green-Flag vs. Yellow-Flag Laps
So let’s separate out green-flag and yellow-flag laps, and then make the same plot as before.
A different picture emerges…
- Four of our lap leaders (Hill, McDowell, Ware, Harvick) led only yellow-flag laps.
- Five drivers led one lap, but three led only yellow-flag laps. Johnson and Byron led green-flag laps.
- While Keselowski and Truex, Jr. both led 6 laps, all of Keselowski’s lead laps were green, while 1/3 of Truex, Jr.’s were yellow.
- Wallace, Blaney, Byron and Jones only led green-flag laps.
Revised Green-Flag Laps Led Plot
If we now plot ONLY the number of green-flag laps led, we get a different picture.
- There are now only 14 distinct leaders instead of 18
- The same three top drivers still led the largest number of laps
- Although Buescher led more laps than Jones, Jones led more green-flag laps than Buescher
- The order changes
Holding the Lead Under Yellow
Denny Hamlin led the first 16 laps of the race, during which there were three yellow flags. He kept the lead for at least one green-flag lap after each of those yellow flags. Those should count for something, right?
It’s one thing to be leading when a caution comes out. It’s another to take the lead because a caution comes out. I felt like drivers should get credit for cases in which a caution interrupted an otherwise green-flag run.
Even More Detailed Laps Led Breakdown
There are also different types of green-flag laps. There are those you run after taking the lead during a green-flag, and then there are those you run after taking the lead on a re-start or at the start of the race. Seemed to me those should be separated out, too.
Just to be complete, I’ll call the yellow-flag laps led that don’t qualify under my earlier definition ‘Non-Quality YF Laps’. Now let’s plot the whole thing again.
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- GF Laps Led:
- GF/Race Start Laps Led are laps the polesitter led before someone else took the lead. I wanted to capture that for future study of polesitting advantages
- GF/Restart Laps Led mean the driver took the lead on a restart
- YF Laps Led only count those laps led by drivers between leading green flag laps.
- YF/NQ Laps Led are those where the lead was taken under yellow. NQ is non-quality. NASCAR (and I) use ‘quality’ for things that are more ‘earned’, so it seemed fitting.
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What That Means For This Race
There were 18 distinct leaders, but only 13 drivers who led quality laps.
Jimmie Johnson led one green-flag lap and Tyler Reddick led two. They were hard-earned, legit laps, but you could argue that leading one or two laps isn’t that significant. If you buy that argument, that brings our quality leaders down to 11.
Although Elliott led a good number of laps (27), only 44% of were quality laps.
Erik Jones ran a pretty good race, running more green-flag laps than Chase Elliott. The same goes for Almirola, who led fewer total laps than Dibenedetto, but led more green-flag laps. What you can’t see on this plot is that Almirola only ran 57 laps of the race.
Lead Changes
Breaking down laps led also provides insight into lead changes. There were 58 lead changes at Talladega.
- 13 lead changes happened under the yellow flag
- 7 happened on restarts
- There were thus 38 lead changes during green-flag racing.
We can break down lead changes for all recent Talladega races the same way we’ve done for laps led.
You can see from this chart that sometimes (especially when there are a lot of cautions) there are a lot more yellow-flag lead changes than others.
But Talladega and Daytona are exceptional because pack racing means lots of lead changes. So let’s use another track as a second example a different track. I picked Dover because lead changes there vary wildly.
All numbers are normalized to 400 laps so we’re comparing apples with apples. Notice the four races I’ve put red arrows on. They each have roughly the same number of lead changes (about 20), but look how the composition of those lead changes varies!
| Race | % Green Flag | % Green Flag Restart | % Yellow Flag |
|---|---|---|---|
| 2010-12 | 75.0 | 20.0 | 5.0 |
| 2013-29 | 52.6 | 5.26 | 42.1 |
| 2020-24 | 66.7 | 13.3 | 20.0 |
| 2020-25 | 6.7 | 20.0 | 73.3 |
Note especially the last two races, which took place on consecutive days. They had exactly the same number of lead changes, but if you only look at lead changes, you miss how different the races actually were.
Conclusion
NASCAR does a great job providing statistics for fan and data geeks. But, with a little work (or just check my race reports), you can gain much greater insight into drivers’ strengths and weaknesses at different tracks.
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