Plate Appearance Outcomes Over the Years

We know that the three true outcomes have been increasing in recent years, but I’ve never seen a good graphical representation of it. I’ve been wanting to examine this data for a while—a conversation with a friend last night spurred me on to do it.

The goal was to track the outcomes of plate appearances over the years, categorized into plays that involve ball-bat contact and those that don’t. The greenish areas in the chart are the “contact” plays, and the reddish areas are the non-contact outcomes. The major takeaway for me is that, over the last 75 years or so, strikeouts have increased by about the same amount that in-play outs have decreased. (In-play outs are balls in play that are not hits, or, in other words, outs that are not strikeouts.)

I was surprised that the decrease in contact plays overall has not caused a proportionate decrease in the percentage of hits. The percentage of hits (singles, doubles, triples, and home runs) has stayed remarkably constant from 1940-2019, never going outside the range of 22-24%!

Likewise, the percentage of walks has been more consistent than I expected. It has been within the 7-10% range since 1936. Also, there’s no clear recent trend in walk percentage, unlike the case for strikeouts.

Although recent home-run percentages (2.7% for 2010-2019) are higher compared to the 1980s (1.9%), they aren’t that different from the “steroid era” (2.5% for 1990-2009) or the 1950s (2.4%).

One way to look at it is to say that the contact plays (green) are “exciting,” while the non-contact plays (red) are “boring.” By that measure, in 1973 (when I started following baseball) 76.7% of plate appearances were “exciting.” In 2019 that figure had dropped to 67.3%, so one could say that the game is only 88% as exciting now compared to when I starting following it.

By the way, this is just a presentation of the data. I’m not getting into the reasons for why the percentages have changed.

Miscellaneous notes:

  • The raw data is from the excellent Baseball Reference site.
  • I chose the National League because it’s the longest continuous league. Excluding the American League avoids effects of the Designated Hitter.
  • I excluded the 2020 season because of the relatively small number of games and because of the DH in the NL.
  • The “other” category collects outcomes like catcher’s interference.
  • Reaching base on an error is included in the “in-play outs” category, because such a play is officially scored as an out for the batter (but for the error).
  • The home-run statistics include inside-the-park home runs. They are very rare today, but they accounted for about 35% of home runs in 1901.
  • Statistics for sacrifice hits were not recorded prior to 1894, and sacrifice flies were not always in the scoring rules. No matter—they should all be counted in the “in-play outs” category.
  • Prior to 1889, more than four balls constituted a walk.

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