Local horseplayers might struggle at Laurel in the fall and suffer indignities at Bowie in the winter, but they could always be comforted by one thought: the Pimlico season was coming.

At no track in America was picking winners easier; a handicapper who understood the nature of Pimlico's racing strip could feel sublimely confident of making money there. For while the sport is ordinarily filled with myriad complexities and subtleties, that one-mile dirt oval could render them all irrelevant. It often gave such advantagesto horses on the rail and horses with early speed so greatly that nothing else mattered. In many seasons a bettor could make a profit by blindly boxing the horses in post positions one, two and three in every 1 1/16-mile race.

But this spring the Pimlico money tree has failed to bloom. Among even knowledgeable handicappers, the question, "What's going on here?" is being asked.

As much as bettors loved the Pimlico racing strip, trainers and jockeys raised complaints about it last year. Trainers told General Manager Chick Lang that it was too hard. Jockeys said it became too slick when it was wet. Everybody agreed that it dried out too slowly after a rain. So Lang had the soil analyzed and found that the ratio of loam to clay was out of balance, and that was the cause of all the problems. And so Pimlico's management spent $165,000 to rebuild the track.

The jockeys were happy. The trainers were happy. But bettors were soon mystified.

Good horseplayers love a consistent bias like the one that prevailed at Pimlico in previous seasons. They can deal with a track that is perfectly normal, with no biases. But when the tendency of the track seems to change from day to day, they go crazy.

For the first few days of the meeting, Pimlico looked like the old Pimlico. The first three exactas of the season were 3-1, 3-2 and 1-3. On some of these days, however, speed on the rail would dominate the early part of the card and closers the late part of the card. On one day, March 26, every horse who got to the rail died. On another day, April 4, stretch runners won every race, something that hasn't happened at Pimlico within memory.

What's going on?

Because its turns are sharp and not severely banked, the contour of the Pimlico track naturally favors horses on the rail; it is hard to accelerate on the outside of those turns. But the track has a crown (to facilitate drainage) and so the loose soil can drift down to the inside to make it deeper and negate the natural advantage of the rail. On Sundays the track is usually "graded"--dirt is moved off the inside--to make its depth uniform.

But, Lang said, "Last Sunday we couldn't grade the track because it was so wet. The prior Sunday was Easter and I would have gotten the Scrooge award if I'd had them grade it then."

This may account for the recent success of stretch runners at Pimlico, but often there are no logical explanations for the appearance and disappearance of track biases.

Last spring, on the day before the Preakness, no special work was done on the track and no change in the weather occurred, but from out of nowhere there appeared an extraordinary bias that carried nine straight speed horses to victory on the rail.

So it is never possible to be sure how or when a racing strip will develop a bias. But one thing does seem certain: The good old days of easy pickings at Pimlico are over.