The Dirt on Kentucky Derby Mudders

Unpredictable spring weather in Kentucky often sends handicappers scouring the pedigrees of Kentucky Derby (G1) contenders for any hint of off-track affinity in the ancestry. A colt whose sire or dam handled the mud should have a stronger likelihood of finding success in the slop is a common angle, and some supporting anecdotal evidence exists.

Curlin   won the 2007 Breeders' Cup Classic (G1) over a sloppy Monmouth Park track and also took the 2008 Jockey Club Gold Cup (G1) in the mud at Belmont Park, and his son Exaggerator  ticked off wins in sloppy renditions of the 2016 Santa Anita Derby (G1), Preakness Stakes (G1), and Haskell Invitational Stakes (G1). Birdstone broke his maiden over a muddy track by 12 1/2 lengths (but lost a sloppy 2004 Kentucky Derby), and his son Mine That Bird  splashed home the upset winner of the sloppy 2009 Derby. Empire Maker  won both of his off-track starts and sired Icon Project , who demolished a grade 3 field by 13 1/4 lengths over a muddy track.

One can just as easily find examples where the theory doesn't apply. Curlin's son Palace Malice   lost both of his sloppy track starts, as did champion son Good Magic  . Empire Maker clearly loved the slop, with wins in the Belmont Stakes (G1) and Wood Memorial Stakes (G1) in the mud, but was by Unbridled, who lost three of three off-track starts. Grindstone and Smart Strike, the sires of Birdstone  and Curlin, respectively, did not start on an off track in their careers.

This mix of examples made BloodHorse MarketWatch turn to the statistics to see if the theory has any merit. We analyzed all North American dirt starters from 2018-22 and the sires and dams of those runners. More than 800,000 starts were made by runners whose sire and dam also both made at least one start. Of those, 106,396 (13%) were off-track starts (a dirt track not labeled fast or good). The baseline for the breed is 13.9% off-track wins from off-track starts.

We next divided the runners into overlapping groups based on their parents' success on an off track: runners with sires that won on an off track, runners with dams that won on an off track, and runners with both parents that won on an off track. Horses with an off-track-winning sire claimed an off-track win percentage of 14.1%. Runners out of dams that won on an off track fared slightly better in the slop, at a 14.6% clip. Lastly, runners with both parents successful on off tracks won at a 14.8% rate.

While there was a slightly increasing gradation in the categories, favoring the influence of the dam over the sire, there was less than one percentage point spanning the lowest to highest win rate among those categories.

Overall, there seems to be little off-track advantage with slop-loving parents, but MarketWatch did see some sires whose progeny are particularly successful in the mud, though not necessarily as a reflection of the sire's own off-track performance. Some sires' progeny actually perform better in the slop than on a fast track. Silent Name's progeny win off-track starts at a 15.6% rate, while their win rate on good or fast tracks is just 8.0%, representing a 94% increase in winning performances on an off track. Lane's End's Tonalist   has the highest off-track win percentage of active North American stallions (with at least 100 off-track progeny starts 2018-22) at 23%, well above the breed average and also above the win rate of his starters on fast or good tracks (16.8%, giving an increase of 37%).

Meanwhile, Calumet's Keen Ice   (by Curlin  ), sire of 2022 fast-track Kentucky Derby winner Rich Strike , sires runners with an apparent distaste for the mud, as they post a 49% reduction in win rates on an off track compared to good or fast conditions. Freud   has just 6.8% progeny wins from off-track starts, 44% worse than his progeny's success rate on favorable track conditions.

The leading and trailing top 20 sire charts on page 78 contain contradictions to the theory. Curlin is represented as a sire by two sons on the leading 20 sires by off-track performance in Palace Malice and Exaggerator, but also has son Keen Ice on top of the trailers list. Similarly, Unbridled's Song has Liam's Map   and Unbridled Express   as leaders and Mission Impazible  as a trailer; Awesome Again  is represented on both lists by Oxbow   (leader) and Paynter   (trailer). Super Saver  , winner of the 2010 Kentucky Derby in the slop, has two sons on the trailing list, including Runhappy  , who had two off-track wins as a runner himself.

Coming in to this year's Kentucky Derby, many of the leading contenders have already tested out a sloppy track. Two Phil's  romped home in the sloppy Street Sense Stakes (G3) at Churchill Downs last fall. Forte  handled a sloppy, sealed track with aplomb in the Hopeful Stakes (G1). Confidence Game , Angel of Empire , Raise Cain , Tapit Trice , and Rocket Can  have each won at least one start over a sloppy or muddy track. Three of those seven contenders had at least one parent win over an off track; both the sire (Hard Spun  ) and dam (Mia Torri) of Two Phil's earned at least one off-track win.