New Ball Made Big Difference In Japan

One significant yet seemingly underreported story has been the introduction of a uniform baseball in Japan’s professional baseball league, the Nippon Professional Baseball League (NPB) before the 2011 season. As detailed in a recent Brad Lefton New York Times article, the NPB agreed to contract with Mizuno as the exclusive supplier in a rule change that was part of a “conscious effort to make the baseball much more similar [to the American one] than before.”

In part, the change was spurred by the differences in baseballs previously used in Japan to those used in international events such as the World Baseball Classic (W.B.C). In the words of NPB Commissioner Ryozo Kato, “an impetus for the uniform ball was seeing with my own eyes the difficulties Japanese pitchers had with the different ball at the W.B.C.”

An interesting byproduct of the uniform baseball was the significant offensive decline that occurred in the NPB last year. Without running a rigorous statistical analysis, a surface look at the artificial numbers certainly seem to agree.

Pacific League
Year AVG OBP SLG HR
2011 304 374 458 19
2010 324 404 504 24
Central League*
Year AVG OBP SLG HR
2011 295 355 442 19
2010 326 401 502 24
* Averages taken among Top 10 leaders in each respective category. The NPB is split into two leagues, the Pacific and the Central league. The structure is similar to the National and American league in MLB.

The Pacific League average ERA dropped from 3.94 to 2.94. The Central League average ERA dropped from 4.13 to 3.06.

What does this mean for the Japanese free agent market?

The answer is simple. Without drawing specific conclusions with only one year of data, be sure to account for the different offensive environment when evaluating an individual player’s statistics in 2011 versus his career numbers. A better statistical season for a pitcher may not necessarily represent an increase in skill. Similarly, a worse statistical season for a hitter may not represent a decline in skill.

Besides the cultural and language adjustment, this change adds another variable that team’s must consider when evaluating how a player will translate to the States. As more statistical data is compiled over the next few years, it would seem to reason that the change would only help MLB teams in their evaluations. 

International | #2011 #International Affairs

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