As that breakthrough approached, Baffert was often sentimental and philosophical about his own rise from a third-rate jockey on the bush tracks of Arizona to one of the world’s pre-eminent trainers.

Baffert spoke about how a severe heart attack in Dubai had made him face his own mortality. He said he was hurt by an unflattering 2013 report by California regulators after seven horses had died in his care. The report said that Baffert had been giving every horse in his barn a thyroid hormone without checking to see if any of them had thyroid problems.

Baffert also spoke about how a narrow loss in the 2012 Derby, by a horse named after his son Bode, had made him seek inner peace.

As Justify followed in American Pharoah’s footsteps, horse racing appeared to have an even stronger chance at stirring back to life. But after 30 racehorses died from injuries at Santa Anita Park in California over the winter and spring, the industry found itself back on the defensive. The Los Angeles County district attorney’s office began an investigation, and California lawmakers and animal rights activists called for more regulation and transparency, especially when it came to drugs and horse safety.

Baffert, 66 , with his five Kentucky Derby winners and two Triple Crown champions, assumed a role as the sport’s affable statesman. In May, in the wake of the Santa Anita deaths, he was the star attraction in support of the California horse racing industry, traveling to the State Capitol in Sacramento to defend his sport before lawmakers.

Baffert told them that the deaths had increased awareness among his colleagues.

“I think the trainers are going to do a better job of policing themselves,” he said.

On Thursday, however, others were forced to defend the sport because of an unflattering narrative in which Baffert was a central character.