Throw It Like a Ballplayer

providing baseball commentary and ponderings since April 2010

Punctuated Home Run Equilibrium: Part II

Posted by dannmckeegan on May 26, 2010

This is the second part of a multi-part series examining the historical rise in the rate of home runs per game in MLB.  Inspired by J.C. Bradbury’s ( position that steroids are a less significant aspect of the home run spike of the last fifteen years than is commonly accepted, I am exploring 90 years worth of home run data in light of the changes that have happened outside of the batter’s box and off the rubber.  This section will examine the first major spike upward in home run production, which occurred in the time of the Babe.  The chart below is a product of Mr. Bradbury’s research.  I stress today again, as I did in part one, that I would have avoided connecting the data points.  Connecting the data points via line segments helps to hide their meaning rather than reveal it.

HR per G chart

The 20s: Wave #1

Each era has a history behind it, both in the popular mythos and the analytical study of baseball history.  The death of Ray Chapman in 1920 led to the use of clean and well-kempt baseballs rather than the filthy, muddy, and worn-out ones that had been used previously.  This caused some physical changes in how pitchers could pitch.  It became harder to hide the scuffs and scratches, let alone find a grip.  Spitballs largely vanished from the game, with the pitchers who exclusively threw them soon to follow.  Meanwhile, Babe Ruth’s arrival in the Bronx led to the popularization of the out-of-the-park home run and inside-the-park beer run.  As Tom Glavine and Greg Maddux made clear to us, “Chicks did the long ball.”  In 1921, the second-place Cleveland Indians had 42 team home runs.  The Yankees, who would lose to the Giants in the World Series, had 134.  Led by High Pockets Kelly’s 23, the Giants had hit 75 home runs during the season.

By 1926, only the seventh-place Browns joined the Yankees above 70 home runs, while Ruth alone outslugged 5 of the other 6 teams in the American League.  Over the next few seasons, power increased.  In 1929, 595 home runs were hit by AL teams, up from 424 in 1926, a 40% increase.  The 1929 World Champion Athletics were led by two 30-home run men in Jimmie Foxx and Al Simmons, while the Tigers had five players in double figures.  While Gehrig had become a powerhouse in New York alongside Ruth, the Red Sox were slowest to embrace the idea: they still had only 28 homers in the 1929 season.  The NL by 1929 had four teams over 100 homers, with the Robins of Brooklyn tallying 99.  Oddly enough, the Braves joined their AL Boston brethren in avoiding the long ball.

Hack Wilson

Chicago Cubs slugger Hack Wilson (1926-1931 with CHC). Image from

While the home run did not correlate completely with winning, there was plenty of evidence to suggest that hitting the ball very, very far was a good thing for the offense.  Neither Boston team was particularly competitive in this period.  The Braves didn’t get to an above-.500 record until Wally Berger developed into a threat in the early thirties.

But there are also some troughs.  Specifically, home runs dropped in 1931 and 1933 after a peak in 1930.  The 1930 peak and 1931 plunge are largely attributable to two players alone.  In 1930, the National League was home to 892 of MLB’s 1,565 home runs.  Of those 1,500 homers, over 5% were hit by a pair of Cubs who had colossal career years.  Catcher Gabby Hartnett and outfielder Hack Wilson would combine for 93 HR and 313 RBI in 1930, but 1931 would see their production drop to 21 homers and 131 RBI combined.  Home runs across the majors dropped to 1069 in 1931, a fall of 496.  A full 14.5% of the net drop – one-seventh of the whole thing – belonged to Hartnett and Hack.

What we learn here is that it is dangerous to look at cumulative data without examining each of the data points.  There were a number of other hitters around baseball whose numbers fell a bit in 1931 compared to 1930, but none so drastically as those two Cubs.  However, an adjustment by pitchers to the changing game was inevitable.  As Stephen Jay Gould and Niles Eldredge (.pdf file) described evolution in their theory of punctuated equilibrium, the changes would occur in fits and starts.  The ball changed for safety, but allowed hitters to gain an upper hand on pitchers.  Pitchers had to experiment (and often fail, much to the detriment of their team’s “fitness”) with pitching to survive.  Combine that with Wilson and Hartnett’s great seasons in 1930, and it’s easy to understand why the rate of increase leveled out for a period.

As we prepare to move on from the Roaring Twenties towards World War II and beyond, let’s take into account the preeminence of unintended consequences of both drastic and simple actions.


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