The year 1984 may not seem to have been an especially memorable one for thoroughbred racing. It produced few great horses, great races or moments of high drama.

But this was, in fact, a year of profound and dramatic change in the horse business. Economically, this multibillion- dollar industry was turned topsy-turvy, and the effects of what happened in 1984 may have beneficial effects on the sport for years to come.

What happened to the thoroughbred industry can be neatly illustrated by the checkered fortunes of a horse named Providential. In 1981, the colt won the Hollywood Turf Cup and the Washington, D.C. International. He soon was syndicated and retired to stud, just as almost all good horses were retired as soon as they had established their credentials.

Why run a top horse in an effort to win a few hundred thousand dollars when his progeny might sell for millions at yearling sales? The breeding shed was the place to make big money with a thoroughbred.

Providential went to Kentucky, where his stud fee in 1982 was $30,000. His first foals were born in 1983. His offspring went to yearling sales in 1984. Eight of them passed through auction rings, and the median price they commanded was $7,900. Everybody who sold a Providential yearling took a financial bath.

The stallion still hasn't been proved a success or a failure -- his progeny won't start racing until 1985 -- but already his stud fee has been slashed to $10,000. Providential was a victim of the laws of supply and demand that have affected the whole industry so dramatically this year.

When Arabs started paying astronomical sums for yearlings in the late 1970s, the whole breeding industry started to boom and there was a mass stampede to get a piece of the action. Breeding partnerships and corporations sprung up overnight; long-established racing stables started to sell their yearlings, too. So many people were trying to play the game that they drove the costs of mares and stallion services sky high.

A few breeders did hit the jackpot by selling a high-priced yearling to Arabs or to Robert Sangster. But the vast majority found there were too many sellers and not enough buyers in the market. There was such inadequate demand that many sellers couldn't even recover the stud fees they had paid in 1982, much less make a profit.

The industry newsletter Racing Update calculated that of 364 stallions who had five or more yearlings in this year's sale, 13 producted a net profit. Of 75 stallions like Providential who were represented by their first crop, 74 lost money on the average.

This was a broad-based disaster, and one of its first effects has been a decline in stud fees for 1985. Even more important, current economic conditions must change the way owners view the choice between sending a horse to stud and keeping him in training.

Largely because of the creation of the Breeders' Cup, the opportunities for a good racehorse have never been more enticing. Slew o' Gold earned $2.6 million in only six starts this season; John Henry has made $2.3 million; Wild Again $2 million.

If the owners of a horse like Providential reached the end of the 1984 season with a healthy animal, they probably would conclude that it made more sense for them to race him in 1985 than to stand him at stud for $10,000 in a tough, overcrowded market.

Instead of being whisked off to stud prematurely, good horses are more likely to stay in training, which will create more interesting competition and (one would hope) more fan interest. The drubbing that so many breeders took in 1984 surely was good for the sport in the long run.