It's a basic physics equation. Six foot does not go into nine stone. It's unfortunate. However, the laws of nature eventually trump even the most stubbornly determined will of man, and Joseph O'Brien is just the latest to have succumbed to the intransigence of nature's scales.
Far from writing a premature postscript to a riding career still in its relative infancy, it is rather to acknowledge instead the greater realities.
Most jockeys fail to record even a single Group One victory in their career, but in addition to his two wins in the Epsom Derby, O'Brien, not yet 22, has also enjoyed success in the Irish Derby, at the Breeders' Cup and on World Cup night in Dubai. There yet may be more to follow, but for the meantime the pick of the Coolmore crop will be partnered by Ryan Moore.
O'Brien junior was the latest name engraved on one of the most distinguished rosters of jockeys ever retained by any patron in the history of the sport. Previous incumbents, idols like Roche, Kinane, Spencer, Fallon, Murtagh each occupied the top spot at Ballydoyle for a time. Rarely, if ever, has one operation commanded such a roll-call of horsemanship in its tenure. Ryan Moore is the latest name to join the already elite list.
From Epsom to Santa Anita, Sha Tin, Moonee Valley, Meydan and Kyoto, Moore can commonly be regarded as the best rider in the world today, riding at the peak of his powers. His recent alliance with Coolmore has exploded from the blocks in the best possible way, with a rare Guineas double at Newmarket last weekend followed by victory in both the Cheshire Oaks and the Vase at Chester's cardinal fixture.
Horse racing perennially suffers from an identity crisis, with its split personality of sport on one side and business on the other vying for supremacy. Even at grassroots, there are economic realities to participating in the sport. The humblest breeder or trainer needs to balance the books. After all, there is no sport in going broke.
At the Coolmore level, competing globally, stakes are far higher and the margin for error far smaller. Not for nothing does the world's pre-eminent bloodstock operation choose to employ arguably the greatest racehorse trainer of all time. It stands to reason then that in concert with the best trainer, it should align itself to the best jockey of the time.
After all, even the purest bloodstock genetic selection and the most meticulous preparation can be undone in an instant through pilot error. Retaining Moore is simply increasing your percentages.
Which doesn't imply Ryan Moore is infallible (see Telescope's defeat in the Jockey Club Stakes), just that he engages more of what Deepak Chopra calls "spontaneous right action" in the heat of the moment than any other Flat rider.
For his new employers, a photo-finish verdict either way can add or subtract €10m to the value of a stallion - it is the ability in the red heat of the most crucial semi-seconds to be able to make the intuitive right choices in the right way at precisely the right time, all on the fly that makes a jockey invaluable.
By parallel, what is it worth to have Lionel Messi on your side when, after 77 minutes of a more ruggedly dour encounter than Mayweather v Pacquiao, he plucks an orchid out of brambles and defies the best 'keeper in the world at his near post; only to follow up three minutes later by tormenting Jerome Boateng into an interpretative dance version of a giant falling maple as the pixie Argentinian lumberjack dinks the ball past Neuer for a second time, on this occasion with his weaker foot. Like all genius in the sporting arena, it brings tears of disbelief to your eyes. And in the commercial arena, it is worth millions.
Ryan Moore creates such demand that although he has prioritised Coolmore and Ballydoyle, his previous boss, Michael Stoute, continues to use his services nonetheless.
The rarest talents are capable of commanding such "unreasonable" terms - supported by the pragmatic view of "better have him riding for you some of the time than against you all of the time". Ruby Walsh managed it for many years with the pick of Paul Nicholls and Willie Mullins from both sides of the Irish Sea.
While Coolmore have got their man, JP McManus is still on the hunt to fill the chasm left by AP McCoy. The choice of McCoy was an obvious one when he made the Ulsterman an offer he couldn't refuse back in 2004 and the jockey more than proved the worth of the investment time and again during the 11 years since. Small wonder JP is taking his time to decide. After all, there is so much riding on it.
Sunday Indo Sport