Trying to project Masahiro Tanaka

Masahiro_TanakaJapanese phenom Masahiro Tanaka is up for grabs this winter and the bidding process is well underway. As we close in on the January 24th signing deadline, things will get pretty interesting as teams weigh how much they’re willing to pay the 25-year-old pitcher. Plenty of teams have already shown interest in acquiring the services of Japan’s best pitcher, and while the Yankees seemed to be the odds on favorites early in the winter, the Mariners, Dodgers, and Cubs have also emerged as favorites according to Ben Badler of Baseball America.

In the NPB last year, Tanaka posted video game-esque numbers, going 24-0 with a 1.27 ERA over 27 starts. Of course, that was in Japan — where the talent level is widely considered to fall somewhere between Triple-A and the majors. Pitching in the MLB is a whole different animal.

So how will Tanaka’s numbers translate across the Pacific Ocean? It’s hard to say, mainly because so few pitchers of Tanaka’s ilk have made the transition. But by analyzing the performances of recent Japanese expats, we can get a decent idea of what to expect out of Tanaka in his rookie campaign. Looking at starters who have made the leap since 2007, two things are clear: 1) Japanese pitchers don’t fare as well in the states as they did in Japan. And 2) their performances tend to be unpredictable. In the graph below, the closer a player is to the red line, the better his performance translated to the MLB in his rookie year.

Japanese Pitchers

Some pitchers, like Hiroki Kuroda, performed almost as well in the States as they did overseas, while others turned into pumpkins as soon as they arrived in the land of the free — erstwhile Yankee Kei Igawa is the poster-boy for this type of failure. Even Yu Darvish, who has experienced plenty of success in the MLB, is just a shell of what he was in Japan, where he posted a 1.44 ERA before his exodus.

Although we’re only dealing with a sample of eight players, we can probably glean a little more about how certain skills translate by digging a little deeper into their stat lines. Based purely on this data, a pitcher’s strikeout rate in the MLB tends to be about 90% of what it was in Japan, his walk rate around 180%, and his homerun rate around 150%. Applying these rules of thumb to Tanaka we get…


Of course, a lot (particularly his HR%) depends on Tanaka’s home ballpark. But this rough estimate works out to about 5.5 WAR over 200 innings, which would be pretty excellent, but also seems a little optimistic. We haven’t seen a Japanese pitcher perform that well since Hideo Nomo came over in the mid 90’s and even Darvish, who was the superior pitcher to Tanaka in Japan, turned in a 3.90 ERA and 3.55 SIERA his rookie year.

But it’s worth noting that Tanaka is a very different pitcher than Darvish. While Darvish strikes batters out with his slider and curveball, Tanaka relies more on his splitter to induce groundballs — a trait he shares with Kuroda, Hisashi Iwakuma, and Kenshin Kawakami, all of whom performed relatively well in the MLB.

The NOM projections done by Connor Jennings are slightly more tepid on Tanaka’s arrival,  but still foresee good things, pegging him for a 3.59 ERA, or around 4 WAR.

The bottom line with a guy like Tanaka is that it’s just hard to know how his skills and stuff will translate. Beyond the stats, cultural disparities can play a role as well, as former player and U.S. émigré Gabe Kapler recently chronicled in a piece for Fox Sports. Tanaka has the talent be an asset for any major league team, but he’s not going to come cheap — he’ll likely command a contract upwards of $100M. At that price, signing Tanaka is a calculated gamble as it’s hard to say just how effective he’ll be when matched up against the best hitters in the world.

Photo by Neier (Own work) [GFDL ( or CC-BY-SA-3.0-2.5-2.0-1.0 (], via Wikimedia Commons

About Chris

Chris works in economic development by day, but spends most of his nights thinking about baseball. He writes for Pinstripe Pundits, and is an occasional user of the twitter machine: @_chris_mitchell
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