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There seems to be quite a bit of fluctuation over time. I don't think I have any good reasons why. Most of the time the correlation is positive, meaning that the better hitters usually strikeout more that average. I am surprised that the correlations have come down since 1980 and that they are not as high today as they were in the 1960s and 1970s. This is because we have guys like Ryan Howard and Adam Dunn around.
It is also interesting that the 1930s were much higher than the periods right before and after. Same for the 1960s and 1970s. The table below shows the top ten batters in OWP for the 1930s and their strikeout rates.
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The simple average of the two strikeout rates for these ten were 7.87% and 9.29% while the rates for the entire group in the 1930s were 6.94% and 7.79%. So the very best hitters struckout alot more than average then.
The next table shows the top ten in strikeouts per AB from the 1930s. The simple average of the OWP of these players was .631. Ruth was over .800 and Foxx and Greenberg were over .700 and three others were over .600.
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In the AL 1913-19, the top ten in OWP had strikeout rates of 5.81% and 6.75% while the averages for the whole group were 6.97% and 7.99%. So in this period and league, the best hitters struckout alot less than average.