A building block of anecdotal descriptions about Japanese baseball is the “Gaijin strike zone.” This implies that foreign hitters in NPB have wider strike zones. A look at play-by-play data since 2003 suggests that such a phenomenon does exist, but primarily for first-year hitters and that from the second season the effect seems negligible.

Former Hanshin Tiger and Orix BlueWave pitcher Ryan Vogelsong said, according to a 2015 Fox Sports story, felt hitters had a smaller strike zone when facing foreign pitchers. This appears to be true in general.

The hypothesis

With access to pitch tracking data, one could ascertain precisely whether or not foreign player get more calls that are outliers, more called balls in the strike zone for pitchers, more called strikes out of the zone for batters.

The data available, however, includes–in all but a few cases–whether a third strike is swung at and missed, bunted and fouled or called.

If there is a gaijin strike zone, we should expect to see two things:

1. Foreign hitters’ share of called third strikes is higher than that of domestic hitters.
2. Foreign pitchers get a smaller share of their strikeouts on called third strikes than domestic pitchers.

The data

The simple answer is that overall, the third-strike analysis does not support the hypothesis that foreign hitters do worse than domestic hitters in called third strikes. But it does support the hypothesis that foreign pitchers might be pitching to smaller strike zones.

From 2003 to 2018 against foreign pitchers, 20.6 percent of foreign hitters’ non-bunt strikeouts were called. Domestic hitters’ called-third-strike percentage was 21.5.

During the same period, against domestic pitchers, foreign hitters’ called-third-strike percentage increased to 21.0. Versus non-foreign pitchers, the domestic hitters’ called-third-strike percentage rose to 22.2 percent.

Hitters vs Pitchers called-third-strike percentages, 2003-2018

	Domestic Hitters	Foreign Hitters
vs Domestic Pitchers	22.2	21.0
vs Foreign Pitchers	21.5	20.6

Take that rookie

If the foreign strike zone does exist for hitters, it appears to be significant for first-year players. First-year foreign hitters had a 23.0 called-third-strike percentage, second-year players 20.9, third-year players 20.0. Whether that’s a reflection of their not knowing the ways of NPB or their status is uncertain, because first-year domestic players get called out infrequently (20.4 percent).

This raises two questions. 1) Do foreign hitters get called out less often because they swing and miss more? 2) Do foreign pitchers get fewer called third strikes because they are better at missing bats?

When one speaks to Japanese players about the trials they went through to secure first-team playing time, the most common theme is the (often justifiable) fear that striking out will earn them a return trip to the farm team. They tend to hack early and often, trying to both get a hit and stave off falling behind in the count. Clearly, the longer domestic players have been competing at the top level, the more often they take called third strikes.

With foreign hitters, it appears to be a one-year adjustment as the called-third -strike percentages plummet after the first season and remain low afterward.

Called-third-strike percents, 1st 6 years, 2003-2018

Season	Domestic Hitters	Foreign Hitters
1st	20.4	23.0
2nd	20.8	20.3
3rd	20.4	20.6
4th	21.7	20.4
5th	23.2	20.1
6th	22.5	18.4

Other comments

Again, what’s needed is pitch specific data, seeing what pitches hitters are laying off outside the zone that are being called strikes, and what pitches are being thrown by whom inside the zone that are being called balls.

Speaking to Tuffy Rhodes recently, he reiterated a common complaint among foreign players, not that the umpiring was inconsistent, but that some umpires acted arrogantly, giving idiotic rationals for missed called strikes, “It’s because you’re tall.”

Looking at this limited data set, I am inclined to think the following:

• That the umpiring doesn’t vary a lot between foreign and Japanese hitters, but that foreign pitchers might have something to complain about.
• Any extreme effect on foreign hitters appears to be a first-year phenomenon.
• I didn’t discuss it here, because I want to look at more data, but I’m inclined to believe that until the Central and Pacific leagues’ umpires were merged together in 2011, they operated extremely differently in deciding called third strikes. The umpires in the more popular and powerful CL appeared to call third strikes less often on players whose managers were famously ornery, such as Marty Brown or Senichi Hoshino. The PL umps appear to have done the opposite and punished the managers who gave them the most trouble, such as Katsuya Nomura.