Racing fans in the U.S. have reason to believe that the thoroughbred species is in decline. This year’s anticlimactic Triple Crown series was the fifth in a row in which the nation’s 3-year-olds were subpar by historical standards. When the Breeders’ Cup is run next month, the year-end championship events likely won’t produce any winners considered superstars.

But this relative weakness isn’t a thoroughbred phenomenon; it is an American phenomenon. In many parts of the racing world — Britain, Japan and Australia, for example — the quality of thoroughbreds appears to be better than ever. Many extraordinary runners have competed in Britain over the past few years, notably the brilliant colt Frankel. The 4-year-old has regularly scored runaway victories against top-class competition, and he will attempt to complete a perfect 14-for-14 career when he runs in the Champion Stakes at Ascot on Saturday. Respected British racing experts already rate him as the greatest thoroughbred in history.

The decline of the U.S. and the ascendancy of Britain is a slow-developing trend that has spanned decades. Racing in this country peaked in the 1970s. Any short list of the best American thoroughbreds would be dominated by runners from that decade, notably Secretariat, Seattle Slew, Affirmed, Spectacular Bid, Forego and Ruffian. Yet since 2000, this country has scarcely produced a horse who could be ranked with such elite company. I could name only one: Ghostzapper, the horse of the year in 2004.

By contrast, Sea the Stars was judged one of Europe’s all-time best runners after capturing the Epsom Derby and Prix de l’Arc de Triomphe in 2009. The extraordinary mare Goldikova won 14 Grade I stakes, including three straight victories over males in the Breeders’ Cup Mile from 2008 to 2010. Harbinger was lauded for delivering one of the most brilliant performances by a British horse when he beat a stellar field by 11 lengths in the 2010 King George VI and Queen Elizabeth Stakes. And then Frankel came along to eclipse them all.

The colt won the 2,000 Guineas, the first of the English 3-year-old classics, with a display of raw speed that, for Americans, might have evoked memories of Seattle Slew in his prime. He sped off to a 15-length lead and buried the field with a performance that was as visually impressive as a racehorse can deliver.

Runaway wins can sometimes be deceptive, but Frankel has verified his quality by the margins with which he defeats rivals of unquestionable high quality. Last year he had a showdown with Canford Cliffs — who had won five straight Grade I stakes and had defeated the mighty Goldikova in his previous start — and trounced his rival by five lengths. In June he annihilated solid Grade I competition in the Queen Anne Stakes at Ascot by 11 lengths.

The venerable company Timeform has assigned numerical ratings to the performances of European thoroughbreds since 1948, and it gave Frankel’s win in the Queen Anne a rating of 147, eclipsing the 145 earned by Sea-Bird, the legendary runner in the 1960s. By Timeform’s assessment, Frankel is the best ever.