When Rockhill Native suffered a stunning defeat in the Bahamas Stakes here Wednesday, trainer Herb Stevens was initially bewildered by his champion's dismal performance.

But by the next morning, Stevens had formulated an explanation for Rockville Native's 13-length loss to Irish Tower: he had not liked the deep Hialeah racing surface.

"Track was dry and loose," Stevens said. "He struggled over it, instead of bouncing over it like he usually does. He wore himself out trying to run over the track. Because he's a free-running horse, his way is to skip over a track. Instead, he was just struggling."

That analysis certainly sounds plausible.If a tennis player's form can vary greatly on grass and clay, if a football team can look like two different clubs on artificial and natural turf, surely a horse can be affected by too deep a track. Perhaps because the explanation does not seem so logical, trainers cite track conditions as the most common excuse for a defeat. l

But after spending years listening to such postrace alibis and correlating them with the horses' subsequent performances, I have formulated Beyer's Law:

Whenever a trainer says his horse lost a race because the track was too dry, loose and cuppy he is talking through his hat.

The fallacy of this kind of rationalization is easily exposed. Indisputably, there are certain track conditions that some horses like and others don't. Some like soft grass, others don't. Some like mud, others don't. But never in the history of the American turf has a trainer been known to say, "My horse really loves a loose, cuppy track." It is strictly a negative concept, employed only after a defeat.

Making alibis for losses is an ancient race track custom, and trainers can ordinarily be forgiven for a harmless bit of rationalizing. But when the trainers start believing their own malarkey, they can do a disservice to their horses -- and even ruin them.

When a good, game horse runs a horrible race he is sending a message that something is wrong. Even if his trainer X-rays him from head to toe and finds no ailment, something is still wrong.

In the fall of 1973, a colt named Tim The Tiger looked like one of the best 2-year-olds of his generation until he ran a dismal race in the Champagne Stakes at Belmont. Clearly the time had come for his season's campaign to be ended, but trainer John Veitch could find no evidence of an injury accounting for the Beimont loss.

So he shipped the colt to Maryland for the Laurel Futurity. Tim The Tiger lost by more than 20 lengths -- and then was found to be injured. He was never the same thereafter. That one bad defeat had been the tipoff.

The annals of racing are strewn with a long list of horses who were ruined because their trainers ran them when they shouldn't. Rockhill Native threatens to become another one.

A gelding, Rockhill Native might have years and years of productive racing ahead of him -- if Stevens were to give him a rest now, and then start from scratch. But the Kentucky Derby is a goal that is hard for any trainer to abandon, especially for a lifelong Kentuckian.

Stevens said he is going to adhere to his original schedule and point Rockhill Native for the 1 1/8-mile Everglades and Flamingo stakes here. If he does keep persevering, Rockhill Native may not be seen again for a long, long time.