Over the past decade, a subtle change has taken place within Nippon Professional Baseball, and it has to do with the strike zone, and the way the two leagues’ pitchers attack opposing batters.
Much has been made about the Pacific League’s superior velocity, and while the average velocity has generally been a little higher in the PL, it is certainly true that PL hitters see more four-seam fastballs than those in the CL as well as more splitters, and more balls in the zone.
Starting in 2018, the Pacific League and Central League switched places, with PL pitchers more likely to challenge batters in the zone, and CL hurlers more likely to try and get batters to chase out of the zone.
Why this happened is a matter of speculation, but I will offer a potential explanation for this. It’s a story that starts with the Yomiuri Giants, and a discovery that helped Tomoyuki Sugano dominate the league for a few years.
Using data obtained from Ira Stevens’ superb website ScoutDragon.com, I have a record of nearly every pitch thrown in Japan since 2009. Since then, umpires have called strikes about 42.5 percent of the time when CL batters did not offer at the first pitch, and 43.6 percent of the time when the league’s hitters did not swing at a 1-0 pitch.
Most teams hover around the league average each year with an occasional outlier, yet, one team is a consistent outlier. Pitchers for the Giants between 2009 and 2021 have gotten called strikes on 44.2 percent of their first pitches that were not swung at, which is more than two standard deviations above the mean.
0-0 CL takes from 2009 to 2021
| P Team | Takes | Strikes | Pct | SD plus minus |
|---|---|---|---|---|
| Giants | 47,147 | 20,861 | .442 | 2.126 |
| Tigers | 47,196 | 20,081 | .425 | -.064 |
| Carp | 47,886 | 20,358 | .425 | -.064 |
| Dragons | 47,358 | 19,965 | .422 | -.451 |
| Yakult | 48,313 | 20,346 | .421 | -.580 |
| DeNA | 48,661 | 20,340 | .418 | -.966 |
When the first pitch is taken for a ball, Giants pitchers have again benefitted from better strike calls (46.1 percent) than the rest of the league (43.6 percent).
1-0 CL takes from 2009 to 2021
| P Team | Takes | Strikes | Pct | SD plus minus |
|---|---|---|---|---|
| Giants | 15,465 | 7,125 | .461 | 2.152 |
| DeNA | 16,843 | 7,347 | .436 | -.044 |
| Swallows | 16,411 | 7,135 | .435 | -.132 |
| Tigers | 15,808 | 6,794 | .430 | -.571 |
| Dragons | 15,891 | 6,839 | .430 | -.571 |
| Carp | 16,150 | 6,897 | .427 | -.835 |
At some point, the story goes, the Giants figured this out. Armed with that knowledge, Giants pitchers with plus command, learned that when umpires are giving your team generous strike calls on 0-0 and 1-0 counts, you can attack the corners relentlessly in those counts without paying the same cost as the rest of the league does for missing.
In his first few seasons, Sugano was among the CL’s leading strike throwers, and one of the leaders in getting batters to swing at pitches outside the zone after he got ahead in counts. In 2017, even when the CL was dominated by strike throwers, who Sugano downward in the rankings in terms of the percentage of his pitches in the zone.
That year, he ranked ninth out of 12 among the CL’s ERA qualifiers in pitches thrown in the zone, according to Delta Graphs, but still finished top of the league in the percentage of swings on pitches out of the zone, and had his career year. That – and, I believe, the introduction about the same time of pitch-tracking systems in Japan — taught the Giants that they could get ahead in counts by staying out of the zone. With the umpires expanding hitters’ strike zones for them, the Giants pitchers have been able to set batters up to chase from Pitch 1.
From 2014 to 2017 the Giants had ranked between first and third in NPB in the percentage of pitches thrown in the zone, in 2018, they were sixth. The past four seasons, Yomiuri has ranked last in zone percentage three times before finishing 11th among 12 teams last year. Yet despite not attacking the zone, the Giants have led the CL in getting opposing batters to chase five times in the last six seasons.
While no team appears to benefit from umpires’ largesse the way the Giants have, their success may have created a new paradigm for the league as the other clubs began to emulate them, but without getting the same results.
The DeNA BayStars, under manager Alex Ramirez and later Daisuke Miura, avoided that trap, while the Yakult Swallows moved away from that in 2021, a switch that has been credited to Hall of Fame catcher Atsuya Furuta’s work with the team in camp that spring.
