Stop Counting Lead Changes

Lead changes are one of the easy-to-pull-out stats from a race. But does that number really characterize a race?

Lead/Caution-O-Gram

Let’s look at a visual summary of the Fall Darlington race. The Caution-O-Gram shows where and for how long the cautions were. The Lead-O-Gram (bottom) shows you who was leading when.

Just by looking at these two graphs next to each other, you can see where there were lead changes due to cautions. You can see, for example, that Erik Jones led two laps early in the race by staying out when others pitted. The same thing goes for Ross Chastain during the stage two caution.

Yes, they’re lead changes. But are they meaningful in terms of the race? I’d argue no.

The reason why I created the Lead-O-Gram was to try to get a visual idea of who was important in the race. From the graph below, you can see that Blaney, Ku Busch and Harvick led for awhile at the start, but that Hamlin and Larson really dominated this race.

The hatched areas indicate unearned leads. E.g. the leader pitted, the cars ahead pitted or were taken out by an accident.

More Detail on the Lead-O-Gram

I’m trying something new with the Lead-O-Grams. I’m distinguishing between earned lead changes and what I’m awkwardly calling unearned lead changes.

  • Earned indicates action by the new leader. These include green-flag passes, taking the lead on a restart or at the race start, or taking the lead on pit row.
  • Unearned (maybe I should call them passive?) means that the new leader got the lead because of others’ actions. The leaders pit during green-flag pit stops; the new leader only has the lead because others pitted. To be sure, the new leader deserves credit for being in the right place at the right time. But sometimes, it’s someone staying out a lap or two, who then pits.

Quality Leaders

Out of the ten distinct leaders in this race, only five (Blaney, Ku Busch, Harvick, Hamlin and Larson) had quality leads — they earned the lead through something they did. And although there were 18 lead changes, there was only one GF pass during the race. The vast majority of the lead changes were unearned.

Much of that is because we had five separate green-flag pit stop sequences that shuffled the lead shuffled around. Let’s look at Denny Hamlin’s track position data for an example. I’m just going to paste it into the graph above.

Superposing Denny Hamlin's track position over the lead changes to show how lead-change numbers can be misleading

Look at the blips in Larson’s track position around laps 154-161, laps 193-199, and lap 230. Hamlin (and others) made green-flag pit stops in the first two ranges — and Christopher Bell inherited the lead on both occasions. At the end of stage 2, Larson pitted and Ross Chastain held the lead for one lap. But after everyone had cycled through each of these pit stop series, Larson was back in the lead.

So, instead of seven lead changes (Larson took the lead from Hamlin, Bell from Larson, etc…), it’s really only one meaningful lead change. Larson essentially led the race from lap 122 to lap 269.

And if you want to take it further, Hamlin took the lead on lap 270 when Larson pitted.

This is why a graph tells you so much more than a number.

But This Was a Good Race!

Yes! Most people thought so as long as their drivers weren’t the ones crashing. But that’s exactly my point. The number of lead changes wasn’t important. The highlight was the battle between Hamlin (who hadn’t won a race all year) and Larson (who’s got the highest average finish among active drivers at Darlington, but has never won there).

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