If you’re a left-handed hitter in Japan or a middle infielder, or worse a left-handed-hitting middle infielder, stop thinking about driving or pulling the ball immediately, before your deviance is discovered and you become an NPB pariah.
After observing that the population of domestic left-handed and right-handed hitters in NPB are not mirror images of each other, I asked Tom Tango (@tangotiger) if this was the same in MLB. He responded that with the exception of a higher proportion of base stealers among left-handed hitters in MLB, there was no significant difference in the populations.
A Japanese left-handed hitter picked at random is much more likely to be a base stealer, much less likely to hit a home run and less likely to strike out than a randomly chosen right-handed hitter.
To get a better look at this phenomenon, I looked at every 300 plate-appearance season in NPB since 1950 and measured how many standard deviations that player was from the year’s mean among players with 300-plus plate appearances.
Then for every player with 750 or more career games, I took the average of his annual variations from each year’s mean in two categories, strikeouts divided by plate appearances, and home runs divided by hits.
Hall of Fame slugger Sadaharu Oh, for example, averaged a strikeout rate variation of -.19 standard deviations from the mean among his 21 seasons with 300-plus plate appearances. He did this while his home run frequency variation was 2.78 standard deviations above the mean.
None of the other seven players whose average career HR variance was +2 standard deviations or more averaged being within half a standard deviation of the strikeout mean.
When you plot left-handed and right-handed hitters on a scatter plot, you see that left-handed hitters mostly occupy the low-strikeout, low-home run quadrant, while right-handed hitters are more evenly distributed. But middle infielders — especially left-handed-hitting middle infielders are even more skewed. Thirty-three of these lefty-swinging middle infielders made the study. Not a single one had an average home run variance better than the mean. Zero.
Kenjiro Nomura has the highest average HR variance of any left-handed-hitting shortstop. The former Hiroshima Carp averaged -.26 standard deviations — his reputation for a power-and-speed type coming from his 1995 season when he socked 32 of his 169 career home runs.
The highest career figure for a lefty-hitting second baseman (-.11) was for Mitsutaka Goto, who played with Orix and Rakuten. Of the 59 right-handed-hitting second basemen in the study, 12 are above average, while 11 of the 71 righty-swinging shortstops were above average.
The tables below are for middle infielders and other players, with the upper lower-left quadrants representing few strikeouts and home runs, and the upper right quadrants above average home runs and strikeouts. Oh isin the upper left quadrant, while players who strike out but don’t hit for power are in the lower right.
Having never studied the subject of platoon advantages in any serious fashion, I was really surprised by the degree to which left-handed hitters spend most of their time hitting off right-handed pitchers. It is fairly obvious when you think about it, but I didn’t bother to look until Tango mentioned the platoon advantage.
He said, and I’m paraphrasing rather than looking up his tweet, that when facing pitchers with the platoon advantage, left-handed and right-handed hitters created essentially the same weighted on base average — in other words, they were equal in value.
That isn’t the case in Japan — at least not among domestic hitters. Left-handed Japanese hitters are more likely to be singles hitters, who tend to hit the ball on the ground to the opposite side of the field. With the platoon advantage in 2018, home runs accounted for 9.1 percent of hits by left-handed hitters, but 14.8 percent of the hits by right-handed batters.
