From The Bloodhorse:
The wheels have been turning at Ballydoyle. The decision to send group I Irish Derby and Irish Champion winner Dylan Thomas to Belmont for the Jockey Club Gold Cup (gr. I) is a departure from their normal strategy. But they have done it before, and it is understandable why they would want to try a different approach.
Their reasoning can be summed up in three words –- Galileo, Hawk Wing, and Oratorio, all top-class colts who ran in the Breeders' Cup Classic (gr. I) without a prep on dirt and made little or no impact on the race. This time, it is apparent that Coolmore does not want to play Russian roulette on the world stage. They want to know if their barrel is loaded or not.
They almost pulled it off in 2000 with Giant's Causeway, who ran a sensational race in the Classic, just getting beat a neck by Tiznow. Coolmore also was successful right off the plane with Johannesburg, who beat a strong field of 2-year-olds in the Bessemer Trust Breeders' Cup Juvenile (gr. I), so they've seen the successes and failures of trying the dirt for the first time without knowing how their horse is going to handle it.
However, it must be noted that both Giant's Causeway and Johannesburg were bred more for the dirt than the turf. In addition, Giant's Causeway was a miler who was able stretch out to a mile and a quarter and use his speed effectively, while the other three were 10-furlong and 12-furlong horses, just as Dylan Thomas is. They, unlike Giant's Causeway, either did not handle the dirt or simply did not have his kind of speed to be competitive against the Americans.
http://bc.bloodhorse.com/viewstory.asp?id=35468