Everybody hits 20 homers

We all know 2017 saw an all-time high in home runs hit, but here are a couple of graphs that show just how staggering the power change has been over the course of MLB history.

Here’s a graph showing the percentage of players qualified for the batting title who hit 20 homers in a given year. For example, in 2014, there were 144 players who had enough plate appearances to qualify for the batting title, and 89 of those 144 (62%) hit at least 20 homers.

The last couple of years are quite unusual. Even at the height of the steroid era, the percentage of 20-dinger qualified players never exceeded 56%, but in both 2016 and 2017 the figure was over 60%.

For a lot of baseball history, any player who hit 20 homers in a season was a regular. This is no longer the case. Check out this plot of percentage of guys who hit 20 homers who were also qualified for the batting title.

A bunch of things about this plot:

  • There are no data points for 1917 and 1918 because nobody hit 20 homers in those seasons.
  • For most years up until 1945, every player who hit 20 homers was title qualified. The exceptions were Babe Ruth in 1925, who played in only 98 games after missing the first seven weeks of the season and Rudy York in 1939, who hit 20 homers playing mainly catcher in 102 games throughout the season.
  • 2017 had the lowest percentage of 20-HR guys qualified for the batting title, at just 76.0%, a shade lower than the 1959 figure of 76.4%. I haven’t been able to figure out what happened in 1959.

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10 Comments on "Everybody hits 20 homers"

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Doug
Editor

Some of the factors at play here include changes in the qualifying standard, and changes in player usage. Since World War II, there has been much greater usage of role players in various configurations, including multiple players sharing a position or positions, and utility players who spell regulars at a variety of positions and accumulate significant PAs, though not often at the qualifying level. Those trends are illustrated in the chart below.

Voomo Zanzibar
Guest

477 PA to qualify in 1959
That 3.1 PA rule was implemented in 1957.

Guys under the threshold in ’59:

Stuart, Snider, Freese, Adcock, Triandos, Neiman, Sievers, Francona

Doug
Editor

117 – number of 20 home run seasons in 2017
117 – number of 20 home run seasons 1901 to 1933
1950 – year when 117 players had recorded a 20 home run season since 1901

Mike L
Guest

Question for the two gurus. Given the increasing use of part time sluggers (many of whom are in platoons) is there any statistical evidence that indicates that players who have significant same-handed deficits keep their power strokes better against opposite handed pitching when not exposed to same handed pitching?

mosc
Guest

I think the best way to visualize this would be the median (not average) number of home runs by qualifying hitters vs year. Your “average” hitter hits more home runs in the past two seasons maybe but I don’t think it’s that out of place if you do that trend.

mosc
Guest

Also if you wanted to normalize this because the number of qualifying hitters varies, I would do “percentage of league wide PA’s by qualifying batters”. If that changes significantly, the median would be meaningfully difficult to compare.

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