Native Dancer's bloodline is credited with creating "precocious, speedy Thoroughbreds that dominate the Derby and other Triple Crown events." By 2008, every entrant in the Kentucky Derby was a descendant. However, he is also faulted for passing on his massive build and hard-pounding stride action, rendering many of his descendants vulnerable to injury. In the mid-2000s, there had been a troubling number of high profile breakdowns, including that of Barbaro (who was distantly related to Native Dancer through his dam.) As the grandsire of both Mr. Prospector and Northern Dancer, the two most important sires of the late twentieth century, a certain degree of inbreeding to Native Dancer became inevitable, potentially exacerbating the issue. "There's a lack of durability right now," said Ric Waldman, the former head of operations for Windfields Farm. "We're dealing with the law of diminishing returns." Vanderbilt's son Alfred G. Vanderbilt defended the stallion's legacy. "All these great horses are not descended from him because he's fragile," he said. "They're descended because he was a champion and he was durable."