- The difference between the fastest male sprinter in the world, Usain Bolt, and the fastest woman sprinter, Florence Joyner, over a hundred meter course is almost an entire second.
- There are two entire weight classes for women (48 and 53 kg) beneath that of the smallest man (56 kg) recognized in the International Weightlifting Federation records. Even the most comparable and larger women's weight class (58 kg) to the smallest male weight class, the women's records are still markedly lower (all units below in kilograms):
Event Men's Record (56 kg) Women's Record (58 kg) % difference Snatch 139 112 24% Clean & Jerk 171 141 21% Total 305 252 21%
- As of 2007, less than one percent of any observable population of women in the United States is 6'0" or taller (PDF), yet there are fourteen major league teams without a single pitcher below that height, per a 2015 ESPN article on the subject.
This is not prejudice speaking, not the silly "your uterus will fall out" nonsense that kept Katherine Switzer out of the Boston Marathon, but the voice of empiricism, i.e. the results of evolutionary sexual differential pressures. Women may be able to run long distances, but they still cannot keep up with men on any event; using the marathon as a specific example, the fastest woman is still thirteen minutes slower than the fastest man. And there are competitive advantages to speed, strength, and (among pitchers, especially) height: per the ESPN article above, the average major leaguer, since 1960, is 5-6% taller than the typical male in the general population. Why would we expect women, who are generally shorter than men, to make it through the same gauntlet of minor league failure that washes out so many taller men? And in the absence of an obvious competitive advantage adhering to a signing team, why on earth would a major league club want a woman player, other than as an Eddie Gaedel freak show and public relations stunt?
Update 2016-05-21: I wanted to present this list of male vs. female tennis matches as an example of the sorts of advantages size and strength confer. While the most famous is probably an over-the-hill Bobby Riggs vs. Billie Jean King match in 1973 (one which the aging Riggs lost overwhelmingly to King, 6-4, 6-3, 6-3), the rest, mostly even matches, went as you might expect:
- Martina Navratilova, nearly retired, lost 7-5, 6-2 to a 40-year-old, retired Jimmy Connors in 1992.
- The Williams sisters, then 16 and 17, unwisely boasted they could beat any 200 or under ranked male player. Karsten Braasch took them up on it and whupped both soundly, defeating Serena 6-1 and Venus 6-2. "I didn't know it would be that hard. I hit shots that would have been winners on the women's tour and he got to them easily," Serena said afterwards.
- And a number of others documented there: Bill Tilden vs. Susanne Lenglen, Bobby Riggs vs. Margaret Court, and in passing stories about Kim Clijsters and Lleyton Hewett, and Chris Evert-Lloyd being beaten by her low-college-tennis-level brother.
That brings up another point: baseball is a game of populations. Finding the top talent is a matter of weeding out failures. Let us posit that the average ballplayer exactly equals the average population male height of 5'10". This means half the male population is that tall or taller. Yet you've already eliminated all but about 2.4% of the female population. So you're now starting to look at extreme outliers on population already just on the basis of height alone, and a tiny fraction of the overall population. How many such women would you have to find in order get even a handful that could compete at that level? How would you even get them into competition to discover that talent? The social issues alone are daunting, but the deck is stacked heavily against women as competitors.