Analyzing 25 years of Kentucky Derby pace fractions

Once upon a time, the Kentucky Derby (G1) was a race in which any running style could succeed. Front-runners, pressers, stalkers, and deep closers alike prevailed with seemingly equal frequency.

But times have changed, and recent years have seen speed horses dominate the 1 1/4-mile “Run for the Roses.” Does this shift represent a statistical anomaly, or a new normal? Handicappers are scratching their heads searching for the answer.

Between 1995 and 2013, a span of 19 years, 11 horses won the Derby by racing in the front half of the pack, while eight winners emerged from the back half of the field. War Emblem (2002) prevailed in gate-to-wire fashion, Mine That Bird (2009) closed from dead last, and the others came from everywhere in between. Generally speaking, the pace fractions determined the most effective running style for any given year; Derbys featuring a sub-:46 half-mile fraction were more likely to produce winners rallying from eight lengths or more off the lead.

Yet recent Kentucky Derbies have unfolded in dramatically different fashion. The last six horses to cross the finish line in first place all employed front-running, pressing, or stalking tactics—in fact, none rallied from farther behind than third place at any call, even when the pace was fast. Case in point? Justify (2018) and Nyquist (2016) showed no ill effects from chasing sub-:46 half-miles.

Why has the complexion of the Kentucky Derby changed so sharply? A popular theory holds that the introduction of the “Road to the Kentucky Derby” qualifying system in 2013 reduced the intensity of the pace by removing pure sprinters from the Derby field, giving an advantage to speed horses.

But this theory doesn’t hold up under scrutiny. Analyzing the last 25 years of Derby pace fractions, broken down in five-year increments, shows that the quarter-mile and half-mile fractions have been just as quick or quicker since the introduction of the Road to the Kentucky Derby. Furthermore, the 2013 Derby—the first held under the new qualifying system—produced some of the fastest fractions in Derby history.

But there has been a shift on a different front. While the early fractions have been holding steady, the 6-furlong and one-mile splits have slowed down significantly. The average times of 1:11.26 and 1:37.06 produced from 2015-2019 rank as the slowest average fractions produced by any of the five-year periods since 1995.

This trend carries over to the final quarter-mile fractions. The run down the Derby homestretch has likewise slowed over the last decade, averaging :26.17 since 2010. That’s a lofty 0.80 slower than the :25.37 average recorded between 2000 and 2009.

Taking all of this together, it’s evident recent Kentucky Derbies have been unfolding in increasingly fast early/slow late fashion. Normally such a race shape is favorable to late runners, so the fact speed horses have been dominating is surprising.

It almost seems as though modern Derby contenders lack the stamina to truly thrive over the testing 1 1/4-mile distance. This could explain why the fast early/slow late fractions have been ironically favoring speed horses. If everyone is out of gas by the top of the stretch, then no one—not even deepest closer—has the energy to produce a genuinely strong finish. Thus, horses positioned near the lead turning for home have a substantial advantage.

Handicappers can argue all day why today’s Derby horses seem to struggle over 1 1/4 miles. Perhaps an emphasis on breeding for speed made an impact. Perhaps changes in training and racing regimens are responsible. Perhaps the Churchill Downs main track has grown deeper and more tiring.

In any case, the Kentucky Derby has changed to more closely reflect the tendencies of U.S. dirt racing in general. Speed is king on the main track, and barring another sudden change in Derby dynamics—not impossible in the historic yet ever-shifting sport of Thoroughbred racing—horses with tactical speed should continue to excel in the Run for the Roses.