Monday, May 20, 2013

Why Dale Earnhardt Jr. and Denny Hamlin Should Race More Often on Saturdays

(This is a cross-post with StatsInsights)

There has been much debate about whether Sprint Cup drivers should also be running in the support series races (Nationwide and Truck series). We've heard terms like “Buschwhackers” or "claim jumpers" to refer to drivers who consistently do the weekend double. We also have seen rule changes to deter veteran Cup drivers from racing in the support series, thereby opening up more spots for younger drivers.

Does running a race the day before help or hurt the performance for Sprint Cup drivers in their Cup races? Do these "warm-up" races earlier in the weekend help a driver when it matters most? Those are the questions we explore in this article.

One school of thought is that the warm-up races are helpful. Drivers stay sharp with extra seat time, and are happiest racing. Besides, it's better than sitting around doing nothing. Proponents of this philosophy also believe that more time on the track serves as a learning lesson for what will happen the next day, giving them a leg up over the Cup competition.

Then there is the opposite theory: that drivers need to stay focused on just their Sprint Cup duties. Advocates of this position argue that any other racing is a distraction from a full commitment to your Cup car. Drivers should spend the weekend improving their car, communicating with their crew chief, and fine tuning the setup. Trying to handle multiple races in the same weekend can be overwhelming physically, mentally, and emotionally. Cup performance will suffer as a result. After all, it’s better to do one thing well than to do two things poorly.

So which theory is right?

As usual, we turn to the data.

I looked at all races run in the big 3 series, starting in the year 2000. I filtered out only the drivers who had a minimum of 15 Sprint Cup races with, and 15 races without, a "warm-up" race. For our experiment, we define a "warm-up" as racing the day immediately prior to a Sprint Cup race.

A first glance at Figure 1 indicates that, for the most part, the warm-up races do not affect average finish in the Cup series. The diagonal line is where the warm-up races have no effect. You can see that most drivers are very near that line.

But let’s take a closer look: this overall effect is not true for all drivers. Some are significantly above or below the diagonal line.

Two things stand out:

1)    Most drivers benefit from having a warm-up race (we can claim this because a majority of the points are above the line)
2)    The drivers that are hurt by warm-up races are hurt a lot (the points below the line are generally much further away from the line than the ones above)

It turns out that most drivers do slightly better with a warm-up race, and other drivers do worse.  The ones that do worse can often do significantly worse.

Figure 2 breaks down these differences. Here we focus on the bigger names in the sport, filtering in drivers with above-average results:

The bars in Figure 2 show the improvement a driver has in average finish when they run a warm-up race the previous day.

Denny Hamlin and Dale Earnhardt Jr. improve about 3 spots in their average finish with a warm-up race already under their belt.

In contrast, Kurt Busch does worse by 8 spots, and Brad Keselowski is not far behind with a drop of 6 spots.

What have we learned today?
This analysis reveals several interesting ideas.

1)    Going back to our pair of competing philosophies around warm-up races: it turns out that both are right; depending on the driver, warm-up races can be a good thing or a bad thing.
2)    The effect is asymmetric: most drivers benefit slightly, and some drivers are hurt in a big way
3)    Denny Hamlin and Dale Jr. should be getting into more Nationwide races, to help their Sprint Cup efforts. Kurt and Brad, on the other hand, might want to consider throwing in more rest days.