2021 Dover Spring Race Report

Equity = Lack of Passing

The 2021 Dover Spring Race will be remembered for Hendrick Motorsports finishing 1-2-3-4. But it should also be remembered for historically low levels of passing.

Both Dover races last year were in August, so I’m not counting them in this report

Caution- and Lead-O-Gram

Here’s the Caution-/Lead-O-Grams for the 2021 Spring Dover race. The last two Spring races at Dover have had two accidents and one spin. Here, we get three accidents.

Of note are the two debris cautions, numbers 6 and 7 on the year. We had a total of 17 debris cautions for all of 2020. At the current rate, we’d end up with 19 or 20 by the end of the season.

There were 7 cautions for 41 laps, or 10.2% of the race. The three-year average for cautions stood at 9.67 before this race due to two high-caution races in 2016 and 2017 (12 and 15 cautions respectively).

The Caution- and Lead-O-Grams for 2021 Spring Dover.
Only five leaders and four quality leaders

The Lead-O-Gram shows the four quality leaders, plus Denny Hamlin. The story of 2021 Spring Dover is that whoever got the lead kept the lead. Alex Bowman’s crew pulled off a really fast pit stop during the first caution of stage 3, took the lead from Kyle Larson and kept it.

In the 2019 Spring Dover race, there were 11 quality leaders. The average over the past three years is 7.33 quality leaders, so 2021 Spring Dover was almost half the average.

Lead Changes

Looking in more detail at laps led, the plethora of cross hatching on the graph below shows that drivers mostly took the lead on restarts.

A vertical bar chart showing laps led by driver and how the lead was acquired.

Historically Low Green-Flag Lead Changes

There were only 10 lead changes in 2021 Spring Dover compared to 15 in the 2019 Spring race. Although the number is down, the big difference is how those lead changes happened: under yellow. Only one lead change was under green.

We’ve never seen so few green flag lead changes this century in a Spring Dover race. The next lowest number is 5, in 2002 and 2014.

Green-Flag Passing

And it wasn’t just the leaders who were having difficulty passing.

A vertical bar chart showing average green-flag passing per lap from 2005-2021.

The 2021 Dover Spring race had an average of 1.8 passes per green-flag lap. Again, that’s by far the lowest since loop data has been available. The next lowest is 2018, where we had 2.7 green-flag passes per lap.

Quality vs. Non-Quality Passes

Quality passes are for position. Non-quality passes including things like passing lapped cars.

You can see from the chart above that we had the smallest number of quality green-flag passes at 2021 Spring Dover at 295. The next lowest was 356 in 2018.

But we also had many fewer non-quality passes at 659. In 2019, we had more quality passes than that!

As a result of the lack of passing, 2021 Spring Dover had 45.9% of the cars finish on the lead lap. Compare that to the average over the previous three races of 33.3%.

Conclusion

I’ll have more to say tomorrow about dominance vs. lack of passing in terms of how this race sorted out. An initial survey of Twitter suggests that people who were at the race thought it was a good race, while those watching on television mostly didn’t.

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About Diandra 451 Articles
I'm a recovering academic who writes about the intersection of science and life. I'm interested in AI, advanced prosthetics, robots and anything that goes fast. Author, THE PHYSICS OF NASCAR and Editor, BIOMEDICAL APPLICATIONS OF NANOTECHNOLOGY

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