Megan McArdle is a Bloomberg View columnist. She wrote for the Daily Beast, Newsweek, the Atlantic and the Economist and founded the blog Asymmetrical Information. She is the author of "“The Up Side of Down: Why Failing Well Is the Key to Success.” Read more opinion SHARE THIS ARTICLE Share Tweet Post Email

Photographer: Saeed Khan/AFP/Getty Images Photographer: Saeed Khan/AFP/Getty Images

Who’s the best tennis player in the world? I couldn’t say. However, I’m pretty sure of one thing: It’s not Serena Williams.

John McEnroe has gotten himself in big trouble for saying pretty much exactly the same thing. In an interview with NPR, McEnroe was asked why he called Williams the best female tennis player, rather than simply the best tennis player. McEnroe seemed confused by the question, and finally replied “Well because if she was in, if she played the men's circuit she'd be like 700 in the world.”

Cue the outrage. How dare he! How dare he?

I’m going to go out on a limb here and suggest that he dared to say it because it’s true.

This is not to take anything away from Williams, whose athleticism stuns me into a near-faint. But even McEnroe’s detractors have had to grudgingly acknowledge that if Williams were playing with the men, at best, her superb athleticism and mental strength might occasionally earn her a win. That’s a pretty strange definition of “best tennis player in the world.”

"Best" is a relative value of course, not an absolute; Tyrannosaurus rex was one of the best in its field, 65 million years ago, but when conditions changed, poor T. rex went from industry leader to the ash heap of history. When we say that someone or something is “the best,” we always have to acknowledge that this judgment is highly dependent on the criteria we’re using to define excellence.

This is approximately the argument many of McEnroe’s critics seem to be making. Unable to refute his core point -- that Serena Williams could not be a world champion if she were regularly competing against men -- instead they’re asking why he would make that the standard for judging whether she’s the world’s best tennis player.

This leaves me just as confused as McEnroe was when the NPR interviewer asked him essentially the same question. Tennis, after all, is a court, a moderate amount of equipment, and some highly detailed rules for determining who wins. The best tennis player is the person who can most regularly defeat the other players under those rules. Unless some sort of terrible plague wipes out hundreds of top men’s tennis players, that person will never be Serena Williams.

I mean, we can wax lyrical about style or mental strength or any other of the nebulous joys of watching sports … but at the end of the day, no one ever says “Well, sure, the Yankees may have gotten more runs, but did you see how graceful the Red Sox looked while they were striking out? Such poise! Such panache!” The team that wins a baseball game is the team that gets more runs, whether they lumber across home plate or dance there on angel’s wings, because that’s what’s written in the detailed criteria that govern the sport. If we want different criteria to judge by, then we’re no longer talking about who’s "the best" at this sport, but about something else, like which team makes best use of its assets. And of course people do think about athletes and teams in this way. Consider the Oakland A's, which through the genius of "Moneyball" in the early 2000s came to be considered a great team. But no one therefore proclaimed that really, they had actually won the World Series.

Serena Williams is fantastically talented, and I am in awe of the amount of discipline and sheer labor it must take to get as far as she has. I can see why people are reluctant to refuse her the honor of “best in the world,” simply because biology did not endow her with the same physical potential with which it endowed many males. Most males also were not endowed with the potential to win Grand Slams in men's tennis. But we don't go scouring the lower ranks of amateur tennis circuits seeking out the player who works hardest or plays smartest. We look for a combination of potential and realized potential. We look for that by seeing who can defeat the most other players.

There are, of course, a few sports where men and women compete on par, like equestrian events, where the strength required comes primarily from the horse, not the rider. (Equestrianism is also, it’s worth noting, one of the few sports at which older people can continue to compete at top levels.) There are also sports where you really can’t compare male and female performance, notably gymnastics, where they compete in distinct events that cater to the relative strengths of the male and female body. But where men and women are playing by the same rules, in most cases, the ladies are doomed to second place. That is, after all, why we have had to set up special women’s leagues so that some of them can win.

None of this denigrates women’s athletics, or the broader feminist project of getting women the opportunities to compete in every field of endeavor. And feminists are right that unequal outcomes are often evidence of lingering discrimination, not proof that women don’t have what it takes. So it’s understandable that they tend to bridle when they hear language like that.

But demanding equal opportunity -- and demanding that people take residual discrimination seriously -- does not require us to go to the absurd lengths of declaring that there are no important differences at all between men and women. Men are, in general, simply better athletically endowed than women. And while there are outliers within their respective distributions, the male outliers are going to best the female outliers in most physical fields of endeavor. This is not fair, but unfortunately, nature doesn’t care about fair.

We should all applaud Serena Williams for becoming the world’s best female tennis player. That's a stunning achievement -- a testament to her physical gifts and how hard she has worked to develop as a player. Williams has earned her titles, her money and her fame, and she deserves to bask in all of it. It is a compliment, and a true statement, to call her the best female tennis player. We won’t add anything to her achievement by subtracting "female" and turning the true accolade into false flattery.

This column does not necessarily reflect the opinion of the editorial board or Bloomberg LP and its owners.