Does Post Position Matter for the Kentucky Derby?


Every year the Derby trainers wait with bated breath to find out what post position their horse has drawn for the most important race in their three-year old lives. Post position may impact betting odds but does it actually impact race results?

Conventional wisdom is that post position 1 (which for many years yielded the most Kentucky Derby winners), is not advantageous in field of 20 horses. In a crowded race, the horse must either break very quickly to get out in front of the pack before coming up against the rail, or risk getting caught in the pack, squeezed back from the inside. Only jockeys like Calvin Borel (“Bo-Rail) have the nerves of steel necessary to hug the inside and get through the smallest holes, riding the shortest track to the finish. Post 2 has similar disadvantages in large fields. The last horse that won from that position was Affirmed in 1978.

Post 20 has the opposite problem. From that position, the horse is close to the outside rail and must either use early speed to get a good position or hang back and hope for a fast close. Big Brown is the last horse that won from the outside, back in 2008.

Audible
Audible most recently won the Florida Derby — by an impressive 3 lengths.

Posts 5-10 are generally the most coveted with in-the-money percentages of 20 percent or higher. Last year’s Derby winner, Almost Dreaming, started from the fifth post position — Audible will be starting from that spot this year. California Chrome also won from the fifth post position.

It used to be thought that horses breaking from the auxiliary gate (posts 15-20) were at a disadvantage, but recent winners Big Brown, Animal Kingdom, I’ll Have Another, and American Pharoah have all won from there. The exception is post 17, which has not yielded any winner.

So what do the statistics say?

As the saying goes, the plural of anecdote is not data. The Thoroughbred Racing Commentary published a very interesting article that shows that, from a statistical perspective, Derby post positions don’t matter much at all.

Data from Keeneland
Although the data makes it look like Post positions 13 and 14 generate far fewer winners, it’s important to note that not all races have 14 starters. Keenelandnraces always have at least four starters but only 1% of races have 14 horses.

The article looks at statistics from Keeneland (a track near Churchill Downs) collected from 3,569 races run since October 2006 and then at the data from the 115 Kentucky Derbies where there are results by post position.

Most important to understanding the data is that not all races have full fields. Therefore, the higher post positions have fewer horses running from them.

Additionally, as the writers point out,
The other reason is that horses at high posts have a harder problem to solve. A horse at post 14 must beat out at least 13 other horses to win. A horse at post 4, by contrast, might have to beat 13 other horses, but it usually has to beat fewer than 10, and it might only have to beat 3. That’s the other reason wins from low posts are more common. Horses at low posts face fewer competitors, on average.

Wins by post position for Kentucky Derby
As at Keeneland, at the Derby fewer races are won from high post positions. Only two horses, for example, have ever won from post 20. But, as at Keeneland, at the Derby the field is not always full. There have only been 20 years when the Derby field was large enough to have a horse at post 20. And to win from post 20, the horses there had to beat out at least 19 competitors. If winning chances were equal from different posts, we’d expect the horses at post 20 to have won about once in their 20 chances. The fact that they’ve won twice suggests that post 20 is not a bad place to start.

So, given all the data, here are the post positions for the 2018 Kentucky Derby. It will be interesting to see what happens on Saturday.

  1. Firenze Fire
  2. Free Drop Billy
  3. Promises Fulfilled
  4. Flameaway
  5. Audible
  6. Good Magic
  7. Justify
  8. Lone Sailor
  9. Hofburg
  10. My Boy Jack
  11. Bolt d’Oro
  12. Enticed
  13. Bravazo
  14. Mendelssohn
  15. Instilled Regard
  16. Magnum Moon
  17. Solomini
  18. Vino Rosso
  19. Noble Indy
  20. Combatant
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