When looking at the spacing of Derby Preps, you have to put all this into historical context and recognize that the recent trend has been to run fewer 3yo preps and allow more time between the final Derby prep and the Derby. Perhaps the sheets philosophy has had a big influence on this change or perhaps the ease of shipping cross-country is the major driver or perhaps both or neither. I am not sure. Less than 20 years ago, it was not unusual to see a lot of horses run their final prep in the Derby Trial, which was held only one week before the Derby! Today this is very unusual. Also, the most prestigious prep has been the Blue Grass Stakes and that was run only 10 days before the Derby up until 1988. Finally, the Wood Memorial was held only 2 weeks before the Derby until 1993 and the Arkansas Derby was held only 2 weeks before the Derby from 1984-1995. It seems the current thinking is that 3-4 weeks is the ideal interval given that all of the major final preps (SA Dby, Wood, Blue Grass, and Aks Derby) are held in that time frame. You might wonder, is the popular thinking supported by the data?

Looking at the only Derby winners (see the list at the end of this message) can be a little misleading. It is probably more insightful to look at the spacing for all the entrants (winners and losers) and see how performance varies by spacing of the final prep. I tried to do a quick check of this for the last 20 years. I don't have info on all the horses for all the years (I had data for 17 of the last 20) so these numbers are not complete and accurate and the sample sizes are not very large for some of the categories (particularly > 4 weeks, which is probably the category of most interest); however, the numbers do suggest that the popular notion that 3-4 week spacing is optimal may be correct and that more than 4 weeks may be suboptimal.

Of course, there are all sorts of biases built into this data. For example, since the most prestigious preps were all in the 10 days to 4 week range, you would expect that many of the horses that took a longer break may have had health problems or may have been a cut below the top horses. Also, as was suggested in another post, maybe it does have something to do with American training methods. Still, I don’t see how the data would support a strong argument for resting a Derby hopeful for more than 4 weeks immediately prior to the Derby.

Anyway here are the numbers. I think the most meaningful numbers are probably the % of starters that finished in the money since those numbers would be more reliable than the % winners for the smaller sample sizes.

# Days before Derby, total starters, % of starters that won Derby, % In-The-Money

7 Days: 15, 0%, 14%
10 Days: 20, 10%, 25%
2 weeks: 89, 5%, 15%
3 weeks: 96, 8%, 21%
4 weeks: 52, 6%, 21%
> 4 weeks: 27, 0%, 3%

An interesting side note is that from 1982 to 1992 no Derby winner came out of the Wood. After that, they switched the Wood from 2 weeks to 3 weeks before the Derby and the Wood has since produced 3 of the last 8 Derby winners. Similarly, the Arkansas Derby was run 3 weeks prior to the Derby in 1983 the year it produced the Derby winner (Sunny's Halo) then it switched to 2 weeks prior to the Derby and failed to produce a winner for 11 years. It then switched back to 3 weeks before the Derby and a few years later produced another winner (Grindstone) and a few years after that a close second (Victory Gallop). The data would suggest that this might be more than just a coincidence.

Finally, here are the last 20 Derby winners along with their final Derby preps:

82, Gato Del Sol, Blue Grass (10 days)
83, Sunny's Halo, Aks Dby (3 weeks)
84, Swale, Lex (2 weeks)
85, Spend A Buck, GS Dby (2 weeks)
86, Ferdinand, SA Dby (4 weeks)
87, Alysheba, Blue Grass (10 days)
88, Winning Colors, SA Dby (4 weeks)
89, Sunday Silence, SA Dby (4 weeks)
90, Unbridled, Blue Grass (3 weeks)
91, Strike The Gold, Blue Grass (3 weeks)
92, LIl E. Tee, Aks Dby (2 weeks)
93, Sea Hero, Blue Grass (3 weeks)
94, Go for Gin, Wood (3 weeks)
95, Thunder Gulch, Blue Grass (3 weeks)
96, Grindstone Aks Dby (3 weeks)
97, Silver Charm, SA Dby (4 weeks)
98, Real Quiet, SA Dby (4 weeks)
99, Charismatic, Lex (2 weeks)
2000, Fusaichi Pegasus, Wood (3 weeks)
2001, Monarchos, Wood (3 weeks)

Good luck to all in handicapping this year's Derby.

Chris