One of the ways that the baseball of yesteryear was different from baseball today was the importance of batting average. With a pitching philosophy that envisioned lots and lots of balls being hit into play and no gauntlet of modern relief pitchers to face, far more at-bats ended with a ball being handled by a defensive player. In 2019, 63% of plate appearances ended with a ball being hit into play. In 1919, that figure was 81%. With half as many fieldable balls, it’s hardly a shock that league batting averages have declined. The effect would be even larger, too, but batting average on balls hit into play was higher in 2019 (.298) than in 1919 (.282).
Hitting .400 was never an easy feat, but it wasn’t some wild, once-in-a-lifetime occurrence when it did happen. The .400 mark has been eclipsed 34 times in major league history, give or take (the number varies depending on just what you consider a major league team in the wild world of 1870s baseball). Ted Williams hit .406 in 1941 and that was it, the last time a major leaguer hit .400 over a season. It’s more than just the lower league batting averages. Baseball’s .252 batting average in 2019 was still higher than in 17 seasons before 1941. Baseball has trended in a more competitive direction and as a league becomes more competitive, you generally expect the differences between players to shrink. That’s true for batting average, too. Just look at the simplest measure of dispersion, standard deviation:

The standard deviation has gotten smaller as time has progressed. Using this simple method, Ted Williams’s .406 in 1941 was 4.46 standard deviations better than the mean batting average of .262 (z-score). A z-score of 4.46 in 2019 only represents a .370 batting average. Nobody’s hit that mark recently, either, but .370 certainly doesn’t feel like anywhere near the same hurdle.
Since it’s the obvious next question, here are the best batting averages by Z-Score. Again, there are more robust ways to look at this, but we’re scrawling on envelope-backs, not landing astronauts on the moon:
Best Batting Averages by Z-Score
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