Throughout the racing season here, it has been nearly impossible to assess the merits of the Derby-age horses. But on Wednesday, some questions about them should finally be answered.

A field of 10 colts will contest the $178,750 Flamingo Stakes at Hialeah, the first major event of the year for 3-year-olds. Since almost all the genuine Kentucky Derby contenders are based in Florida, the race should provide some clues about the spring classics.

Rockhill Native, last season's 2-year-old champion, will be the favorite, but he will be matched against three rivals who have just begun to blossom this winter, Colonel Moran, Superbity and Prince Valiant.

Even though he has more established credentials than any other horse of his generation, Rockhill Native is still an enigma. He ran a dismal race in the Bahamas Stakes here, losing inexplicably by a dozen lengths, but rebounded to capture the Everglades Stakes two weeks ago.

But the significance of that performance is uncertain. The race broke perfectly for Rockhill Native when his two chief opponents, Superbity and Irish Tower, engaged in a suicidal early duel. Rockhill Native sat in third place behind them and swooped past the two exhausted leaders in the stretch. He doesn't figure to have such extraordinary good luck today.

Trainer Tom Stevens said this morning that the gelding is "saucered and blowed" in preparation for the Flamingo. That doesn't make him any less of an enigma.

Superbity ought to improve after that speed duel in the Everglades led to the first defeat of his five-race career. But his No. 10 post won't help him.

The post position draw instead favored Colonel Moran, a speedy colt who will break from the rail. He won a minor stakes race by 10 lengths in his last start, and he will probably be the second choice in the wagering.

Another well-regarded, lightly raced contender is Prince Valiant, who made the first start of his career Jan. 16. He has won three of his four races, improving in each of them.

Perhaps the most intriguing entrant Wednesday is a longshot, Koluctoo Bay. Last fall, he ran one of the most impressive races of the year by a 2-year-old when he captured the Young American Stakes at the Meadowlands in sensational time. He returned to competition here in an allowance race and lost by 4 1/2 lengths to Prince Valiant, but his jockey had him under a stanglehold for much of the race.

Koluctoo Bay's owner, Robert Levine, feels about the Flamingo as many of the owners and trainers do.

"I'm more nervous about this race than ever before," he said. "I'm uptight because it's important for us to get a line on our horse, to see just how he fits in against these horses he's running against. It will probably influence greatly what we're going to do with him."