If he were performing so brilliantly in any other sport, Ron Alfano would be universally acclaimed. The young trainer has accomplished feats at Bowie Race Course this winter that are worthy of the greatest members of his profession.

But the racetrack is a jealous and suspicious little world, where people assume that anybody who wins too many races must have an unfair edge. And so the skeptics who ask "What is he doing?" outnumber those who are hailing Alfano as the best young thoroughbred trainer in America.

Alfano has won with one-third of the horses he has saddled in 1981, but even that impressive statistic does not begin to suggest the extraordinary nature of his achievements. When Alfano takes new horses, he transforms them, in ways that seem to defy logic and the laws of nature.

One of his owners sent Alfano a horse named Preconsent from New York, where in his last four starts he had lost by margins of 20, 22, 14 and 13 lengths. After less than two weeks in the care of his new trainer, Preconsent came to life and won convincigly at Bowie.

Alfano took over the training of Sunny Winters after the colt had finished a lackluster fifth at Bowie. Two weeks later, Sunny Winters defeated some of the best sprinters at the track, trouncing horses who had trounced him in their previous meet.

Alfano acquired Main Stem after he had lost three straight races by margins of 19, 12 and 19 lengths. Main Stem spent only a week in his new barn before he woke up and upset Thirty Eight Paces, a top skates horse who was a seemingly unbeatable 1-to-5 favorite.

What makes Maryland racetrackers so suspicious of these form reversals is the feeling that they have seen this all before. In 1974, trainer John Tammaro was performing Alfano-type miracles, transforming new acquisitions almost overnight, but it turned out that he was the first local trainer to use the potent new drug Lasix. When other trainers got hold of it, they worked miracles, too.

The next age of miracles in Maryland came in 1978, when certain trainers seemed to be accomplishing magic. This happended to be the time when the potent narcotic Sublimaze was being introduced at the nation's racetracks.

There is no evidence that Alfano has ever committed the slightest impropriety, but if he has the expertise to improve horses so much so quickly, he is a candidate for the Hall of Fame.

"I don't know about the Hall of Fame," Alfano said, "but everything is really clicking right now. I've got a very good bunch of horses and a balanced stable. I've got good, hardworking help and good owners behind me. But remember: this didn't happen overnight."

Indeed, Alfano has paid his dues. He worked as a groom for trainer Dick Dutrow, probably Maryland's most able horseman, whose barn has served as a prep school for budding young trainers. He went out on his own in 1973, struggled with a small operation, and as recently as 1978 was still running a modest stable of about 10 horses. But last year he was consistently among the leading trainers at all the state's race meetings, and this year he has exploded.

"I think I'm learning all the time, and I'm a better trainer this year," Alfano said. "I used to second-guess myself about a lot of decisions. Now I'm doing things with a lot more confidence."

Those apparent "miracles" at Bowie have been the result of good, basic horsemanship, Alfano said. "Preconsent was a little anemic when I got him. I got him good and healthy. Main Stem has some talent but he was a little sore until we worked on his ankles.

"I must put in 15 hours a day at this job," Alfano said, "and that's one of the reasons I'm running hot. I hear some snide remarks around the track, but I don't think anybody with a knowledge of this game should accuse me of using drugs."

There, Alfano is wrong; people with a knowledge of this game know that drugs are part of it, and that trainers with access to undetectable narcotics or stimulants will enjoy periods of spectacular success. The one true test of a horse trainer is time. If Alfano can sustain his current level of performance over the years, he will be a candidate for the Hall of Fame.