While we’re on the subject of called balls and strikes in Nippon Professional Baseball, @Student_murmur has done a nice study in Delta Graphs about how the count affects umpires calls, which you can find in Japanese HERE.
Lacking pitch tracking data and having to depend on Mark I eyeball technology, the researcher drew a line around the strike zone in different counts where calls went 50-50. It’s no surprise that the smallest zone accompanies the 0-2 count, and the largest the 3-0 count.
The data from 2017 and 2018 collected by Delta Graphs looks fairly consistent and are consistent with the findings of John Walsh in 2010, which you can find HERE. Walsh found that the area of the strike zone’s vertical plane in MLB was 3.52 square feet with a 3-0 count and 2.42 square feet with
The last post here dealt with pitch locations derived from Nikkan Sports’ pitch-by-pitch data in 2018. These consisted of designated as inside the edge of the zone and outside the edge. I labeled them all borderline pitches, either borderline ball locations or borderline strike locations.
Looking at pitches in these two border zones that were called balls and strikes on 3-0, 0-2 and all other counts in 2018 produces the following tables, where 78 percent of all borderline pitches were called balls in counts other than 3-0 and 0-2. In 3-0 counts it was 60 percent. In 0-2 counts it was 92 percent.
We need to understand that in this study and the Delta Graphs one, the data points are being observed by someone else’s eyeballs and recorded by someone else’s hands. Also, pitchers can worry less about balls and strikes in certain counts. Unfortunately, the same seems to go for umpires.
Borderline called NPB balls and strikes in 2018 with 0-2 counts
| Count | Border Zone | Ball | Strike | Total |
| 0-2 | Strike Zone | 1 | 182 | 183 |
| 0-2 | Ball Zone | 2,122 | 4 | 2,126 |
| 0-2 | Total | 2,123 | 186 | 2,309 |
| Percent | 91.94% | 8.06% |
Borderline called NPB balls and strikes in 2018 with 3-0 counts
| Count | Border Zone | Ball | Strike | Total |
| 3-0 | Strike Zone | 0 | 349 | 349 |
| 3-0 | Ball Zone | 524 | 3 | 527 |
| 3-0 | Total | 524 | 352 | 876 |
| Percent | 59.82% | 40.18% |
Borderline called NPB balls and strikes in 2018 with all other counts
| Count | Border Zone | Ball | Strike | Total |
| Other | Strike Zone | 2 | 11,060 | 11,062 |
| Other | Ball Zone | 39,504 | 135 | 39,639 |
| Other | Total | 39,506 | 11,195 | 50,701 |
| Percent | 77.92% | 22.08% |
