The huge books of mares which many first-season sires are able to attract tell us all we need to know about the novelty factor in modern-day commercial breeding.
Ultimately, of course, a stallion will stand or fall by the success of his offspring, but until he proves himself either a success or a failure he has to rely on the power of belief. As long as breeders believe that he can sire winners, or (in many cases more importantly) believe that he can sire horses that yearling-buyers will think will win races, he will attract mares. Thus many people are prepared to give first-season sires a go, but each subsequent year at stud while he remains unproven, as the novelty value wears off (and as breeders are aware that he might have shown himself to be a dud by the time they come to sell his yearlings), he becomes harder to market, in the view of correspondent John Berry.
Traditionally, the fourth year of a stallion’s career is a hard one for his promoters, as his racing days are a distant memory and he still hasn’t had a runner by the time the covering season starts. One hopes that, for his fifth season, it will then have become easier again to attract patronage, assuming that his first runners have made enough of an impression to confirm his merit.
Extract from Thoroughbredinternet