In 2013, former Mariner Wladimir Balentien broke Sadaharu Oh’s 49-year old single-season homerun record in Japan, hitting 60 homers over the course of a 144-game schedule. The story trickled out to US news services with an asterisk firmly attached. The narrative went something like this: yes, he broke the record, but only because the ball was juiced. In fact, once it was uncovered, those nationalists in NPB were so upset that they demanded the resignation of commissioner Ryozo Kato. While never spelled out in anything like those terms, stories tended to lead the reader right up to the brink of those conclusions. I, at least, accepted that narrative*; it seemed consistent with previous efforts by Japanese players to prevent a foreigner from breaking Oh’s cherished record. In this case, however, the narrative was false- uniquely false, perhaps- but false. All of the facts in the story were accurate, but simply mashed together inappropriately to create a false impression of cause and effect.
*Until Yakyu Night Owl raised forceful objections on twitter.
Juiced or Raised from the Dead?
I took a look at offensive stats in Japan. Here are R/G levels for Japan’s Central (in which Balentien’s Yakult Swallows play) and Pacific Leagues.
It turns out that the ball was “juiced” in 2013, but only relative to 2011 and 2012 levels. In those two seasons, runs were historically scarce in Japan. 2013 levels were up, but slightly lower than pre-2011 levels. Homerun rates tell a similar story. (I’ve included 1964 numbers in the table for reference, as that’s the year that Oh set the original record).
The more accurate version of the narrative (which seems to be common knowledge to everyone involved with Japanese baseball) is as follows: In 2011, a standardized ball was introduced into the league. Prior to that season, each team ordered their own. Offense declined sharply with the new ball, and prior to the 2013 season, someone at NPB (allegedly secretary general Kunio Shimoda) ordered a livelier version and covered it up. Early-on in 2013, just about everyone realized the ball was different, and the players complained that they should have been informed for the sake of contract negotiations. For his part, Kato denied that the ball had changed right up until an investigation proved that it had, after which he received enormous pressure to resign. He finally conceded later in the season, and that news just happened to be reported right alongside news of the Balentien homerun record.
Tanaka and the Dead Ball Era
Two of Masahiro Tanaka’s best three seasons coincided with the Japan’s dead-ball era. In 2011, he threw 226 innings with an ERA of 1.27, then 185 innings and 1.87 in 2012. levels. How much of a boost did Tanaka get from the reduced offense over those two seasons?
*These are estimates, as I don't have Tanaka's complete stat line. They should be pretty accurate.
Well, that’s difficult to say. Tanaka’s numbers improved sharply in 2011 and 2012, but he was equally dominant in 2013, throwing 212 innings with a 1.27 ERA. While the league moved back towards previous levels, Tanaka pitched as if he alone was still using the dead ball. His homerun rate was virtually unchanged.
What about the rest of his peripherals? I hypothesized that a sudden change to a dead ball would boost strikeout rates for power pitchers, as they could tread the upper reaches of the strike zone for swings and misses with less fear of getting taken deep.
It turns out that league-wide, that wasn’t the case. The strikeout rate barely moved. Tanaka, on the other hand, did get significantly better at striking people out. Whether that can be attributed to him leveraging the new ball to his benefit is a question for Japanese Harry Pavlidis. It’s possible that those two seasons simply happened to coincide with the peak of Tanaka’s powers. Regardless, I do think it's notable when comparing him to previous Japanese imports.
What we can say with relative confidence is that over the course of his career, Tanaka has gotten better at controlling the strike zone and keeping the ball in the park. In and of itself, that’s a desirable trait for someone who just signed a long-term deal to pitch in Yankee Stadium.