Many pixels have been spilled regarding the adjustments Japanese pitchers must make transitioning to American baseball. Most attention focuses on the differences in the official baseballs used in the Japanese (NPB) and American (MLB) major professional leagues. The differences in physical dimensions between those baseballs has been of particular interest. This has become a focal point locally after the Cubs signed Shu014dta Imanaga, an elite moundsman coming off eight seasons of very good pitching in NPB.
What we attempt here is to examine the differences in dimensions using specimens readily available for purchase and inspection. We will not try to compare methods of manufacture, internal composition, or relative pregame treatments of the leather surfaces.