Sire: Rock Hard Ten
Dam: Kalahai Cat
Damsire: Cape Town
Trainer: Carl Domino
Jockey: Joe Bravo
Owner: Sterling Racing
Notable Races: 1st, G3-Spiral Stakes
Positives: Black Onyx enters the Kentucky Derby off of a victory in the Spiral Stakes over the Polytrack at Turfway Park. But despite the fact that his last two wins were on turf and synthetic surfaces, this colt has shown the ability to run well and win on dirt (he broke his maiden on dirt at Aqueduct in early November), so I don't think surface issues will be the major question for this colt in the Kentucky Derby.
In his three prior races on dirt, Black Onyx rated a length or two lengths off the leaders, so the plan will probably be to lay close to the front of the pack and stay out of as much trouble as he can through the early stages of the race.
Negatives: While the surface might not prevent Black Onyx from winning the Derby, his pedigree and stamina looks like it could be an issue. Black Onyx's damsire, Cape Town, sports an average winning distance for his offspring of just 6.6 furlongs, and his dam, Kalahari Cat, won three races in her career: two races at a mile on the grass and one at six furlongs on the dirt. Offspring of Rock Hard Ten have an average winning distance of 7.6 furlongs, so there's a bit more stamina on the top half of the pedigree.
One additional concern is his light work schedule the past month: Black Onyx has only two published works since March 15, one on April 13 and another on April 27, both of which occurred at Churchill Downs.