It had to be more than a coincidence that the Kentucky Derby and the Oscar De La Hoya-Floyd Mayweather fight took place on the same day. Those who control the order of the cosmos might be trying to tell us that things have changed. Horse racing and boxing were not only two of the most popular sports in this country a century ago, they were staples of American culture. Indeed, in the early part of the 20th century, most prominent sportswriters wrote about little else. Bat Masterson, for instance, the buffalo hunter and peace officer turned columnist for the New York Morning Telegraph, hated all sports except for racing and boxing.

Masterson would have had a hard time making a living today. Horse racing, which now exists for most Americans only on Derby Day and for a couple of other big races a year, has been largely supplanted by Nascar, and boxing, which once supplied us with our biggest sporting events and most popular heroes — baseball not excepted — is all but extinct as a part of our cultural mainstream, its following diluted by wrestling and mixed martial arts.

Actually, that’s not entirely true. Boxing is doing well in Latino communities, who produce most of the top fighters and the majority of the patrons. This is a segment of the sporting populace almost invisible to the English language press, which is why so many in the sports world were stunned in 1980 to find that a Panamanian, Roberto Duran, was the second biggest draw in the sport, behind only Muhammad Ali. Or in the late-1980s, when Mexico’s Julio Caesar Chavez suddenly emerged, full blown, as the game’s biggest star.

However, for Latin boxers to light the fuse for superfights, there has to be crossover appeal, someone who can stir excitement not only among black but white fans. And Floyd Mayweather Jr. just isn’t that man, as he demonstrated against Oscar de La Hoya.

Mayweather did deserve the decision in Saturday night’s World Boxing Council junior middleweight title fight, but not by much. Those who saw De La Hoya as perhaps having earned a draw — including Mayweather’s father and De La Hoya’s former trainer, Floyd Mayweather Sr. — are the kind of people who give too much reward to ineffective aggression (which is kind of like awarding a baseball player for consistently swinging hard and missing).

There are also those who thought the fight was a resounding victory for Mayweather, like HBO Idiot-In-Residence Max Kellerman, who proclaimed after the fight that “De La Hoya hardly landed any effective punches except for jabs and body shots” — which is not unlike saying that an army didn’t fight well in a particular battle except for its air force and artillery. (Kellerman is a mixed martial arts enthusiast whose main method is to make the simplest possible observations with maximum enthusiasm; he’s the uncontested favorite of a generation who learned their boxing from video games.)

No one wants to say it, because it was obvious that both men were doing their best to give the customers their money’s worth, but the fight was something of a disappointment, not quite lackluster but not a fight that produced genuine high drama. (Which is another way of saying that neither fighter ever seemed to be in real trouble.) De La Hoya, age 34, was probably more victimized by ring rust ( just one major fight in three years) than age. He could probably beat just about anyone else around today besides Mayweather, and in truth, was maybe just a dozen good jabs or so from having beaten him Saturday night. Mayweather may well be, as many claim, the best poundfor-pound fighter in the world, but given the current level of opposition, that doesn’t mean much. He is now 30 years old and presumably at his peak, but in the biggest fight of his career he showed up with no definite plan or style and could not dominate the only first rate fighter he’s ever faced, a man he was an overwhelming favorite to beat resoundingly.

Again, no one wants to say it this way, but the reason the fight was disappointing is Mayweather himself. Worse, after being awarded the decision, Mayweather said he was sticking by his pre-fight promise to retire, which would have the same dampening effect on boxing that occurs very year in horse racing when the Kentucky Derby winner is put out to stud before it has a chance to become a household name. Boxing needs a new superstar to emerge from the hype as the old superstar steps down, and it just didn’t happen. In fact, it appears right now that Mayweather’s only big payday in the immediate future would be a rematch with De La Hoya (who, if he’s smart, will put himself out to stud) — certainly the only match that would tap into the vast and lucrative Latino boxing crowd.

Floyd Mayweather Jr. may not like the idea of being a standard bearer for his sport, but unless he picks up the flag, he stands virtually no chance of becoming the legend he so desperately wants to be. Meanwhile, awaiting Mayweather’s inevitable announcement that he isn’t, as threatened, going to retire, what’s left of the boxing community has to be asking itself: If greatness eluded Floyd Mayweather Jr. last Saturday night, will he ever really achieve it?

Mr. Barra is the author of “The Last Coach: A Life of Paul ‘Bear’ Bryant.”