NPB in the MLB: A Historical Analysis of Pitchers

(Bumped from FanPosts. --Eric)


Baseball, generally known as "America's pastime", has become an increasingly globalized sport over the years. The game has origins are shrouded in the mists of time; no two scholars entirely agree as to just how baseball originated and developed. Two things are more or less certain, however- the game of baseball evolved from ball-and-bat games played primarily in Great Britain, and that Abner Doubleday did not create and codify the rules of baseball ("base ball") in Cooperstown, 1839. As the 19th century came to a close, and the 20th century began, the rules of baseball and the way it was played became more recognizable to us today. National Association (of Professional Base Ball Players, the league's formal name) folded in 1875. The National League was born from its ashes in February 1876. The Western League was disbanded in 1899 and reorganized as the American League in 1901. The inaugural World Series was held in 1903 between the Pittsburgh Pirates and the Boston Americans (who would later become the Red Sox). The Dead-ball era ended in 1920, and the Golden Era began.

It was during this time that Hiroshi Hiraoka came to the United States to study engineering. Exposed to baseball and enthralled by the sport, Hiraoka returned to Japan in 1878 and established the Shimbashi Athletic Club, Japan's first baseball team. The sport took root, and by the 1920s, universities across the island nation were organizing and fielding teams, and playing against one another. The very competitive nature of these collegiate rivalries prompted universities to begin sending student athletes across the Pacific Ocean to America, in cooperation with the government, where they would compete with and learn from American collegiate teams. In 1920, Major League wash-out Herb Hunter (who sports a career .163/.196/.224 batting line in 39 games) organized a barnstorming tour through Japan. His tour was successful and Commissioner Kennesaw Mountain Landis gave Hunter his blessing to conduct more trips- most famous among them was the All-Star Tour of 1934. The MLB All-Stars won all 18 of their games, but the performance of many of the players on the Japanese team led financiers to realize they had something going for them- Eiji Sawamura, for example, a 17-year-old right-handed pitcher, pitched five innings in one game, giving up one run, and striking out nine batters, including Babe Ruth, Jimmie Foxx, Lou Gehrig, and Charlie Gehringer. The Japan Occupational Baseball League- later shortened to the Japanese Baseball League- was established in 1936, and later reorganized into the Nippon Professional Baseball League in 1950.

It goes for obvious reasons, the close relations that American and Japanese baseball organizations had became frosty in the 1940s. Time heals all wounds, however, and by the 1960s, the past was the past. In 1964, the Nankai Hawks- today the Fukuoka SoftBank Hawks- reached an agreement with the San Francisco Giants, in which they sent Masanori Murakami, a promising left-handed pitching prospect, and two other Minor Leaguers to America, where they would play with the Giants' Single-A affiliate Minor League team, the Fresno Giants, as "exchange students". Though originally slated to return to Japan in June, the Hawks seemingly forgot about Murakami, and as a result, he spent the entire year with the Giants in Fresno. He pitched 106.0 innings in Fresno, sporting a 1.78 ERA. In August, the Giants promoted him to the big league club, and on September 1st, 1964, he appeared in his very first MLB game. Fittingly, when he toed the rubber at the newly constructed Shea Stadium that day to pitch against the New York Mets- a game the Mets won 4 to 1- he became the very first Japanese player to ever appear for a Major League team*. Murakami was supposed to return to Japan after the 1964 season, but the Giants refused to allow him to return. Eventually, the two teams reached an agreement with the Nankai Hawks, in which Murakami would remain with the Giants for one more year, but would then return to Japan. He would appear in 54 games with the Giants in 1964 and 1965, pitching 89.1 innings. He did fairly well for himself, striking out 10.07 batters per nine innings, walking 2.32 batters per nine innings, and pitching to the tune of a 3.43 ERA and 2.62 FIP. For whatever reason, perhaps because of the snafu that occurred when the Giants refused to allow Murakami to return to Japan, nearly thirty years would pass before another Japanese baseball player would come to the United States to play baseball professionally.

*In 1936, Connie Mack, impressed by Eiji Sawamura's performance in the All-Star Tour of 1934, attempted to sign him, but the young Sawamura declined, because he was reluctant to leave home (he would die in 1944, after the battleship he was serving on in Japanese Imperial Navy was torpedoed- if he accepted Mack's offer, who knows how his life might have panned out; between 1937 and 1943, he pitched 105 games, had a record of 63-22, accrued 554 strikeouts and possessed a cumulative career ERA of 1.74).

In 1994, the Kintetsu Buffaloes- today, the Orix Buffaloes- got into a contractual dispute with their star pitcher, Hideo Nomo. The 26-year-old, who had a career mark of 78 and 46, with 1,204 strikeouts and a 3.15 ERA, wanted a multi-year contract, and the Buffaloes were not interested in caving to his demands, such as they were. Don Nomura, Nomo's agent, combed over the various formal and informal arrangements the MLB and NPB had mutually agreed upon, and seized upon a loophole in the rules. Hideo Nomo suddenly and unexpectedly announced his retirement from the NPB. According to the 1967 working agreement between the MLB and the NPB, Japanese players were barred from signing with an MLB unless they qualified for international free agent status, or if their team sold their contract to an MLB team. A player who was retired had any current contracts deemed null and void, and as such, could sign new agreements elsewhere without violating any rules. In February 1995, the Los Angeles Dodgers and Hideo Nomo worked out an agreement, and "The Tornado" took his services to L.A. Two years later, in 1997, the Chiba Lotte Marines "traded" the late Hideki Irabu to the San Diego Padres, who in turn quickly flipped him to the Yankees, since Irabu refused to sign a contract with San Diego, stating that he would only play for the Yankees. In 1998, Alfonso Soriano, sore at the Hiroshima Carp for denying him a raise and sick of the intense Japanese training regimens he was not used to, hired Don Nomura as his agent, and exercised the same loophole that Hideo Nomo had. He was recognized by the MLB as a free agent, and signed with the Yankees that year.

In a span of four years, the NPB lost two stars in Nomo and Irabu, and one promising prospect, in Soriano. Because Nomo and Soriano left Japan through rule loopholes, their teams were not compensated in any way. And, because Irabu refused to play for the team that his contract was traded to, the MLB also found itself in a precarious situation. So, in December 1998, the two organizations got together and rewrote their working agreement. The result was the ‘posting system', in which an NPB team would allow MLB teams to place silent bids for a player who was not qualified for international free agency, but wished to play in North America and had the permission of his team. The team who won the bidding process would compensate the NPB team with the amount of their bid, and would enter into an exclusive negotiating phase with the Japanese player. The implementation of the posting system, coupled with Hideo Nomo and Hideki Irabu trailblazing the way, opened the floodgates of Japanese baseball players plying their trade in the United States. Between 1965 and 1995, not a single Japanese ballplayer played in the Major Leagues. Between 1995 and the present, 41 Japanese ballplayers have come to the Major Leagues. This off-season, at least two Japanese players are expected to come to the MLB, another two might, and via the posting system, there are two more candidates who may come to the U.S., including Japan's crown jewel.

Among many baseball fans, ‘experts', pundits, and professionals, Japanese ballplayers are a mixed bag, for many reasons. To get it out of the way quickly, first, racism is a factor in some cases, sadly. More legitimately, however, the level of competition in Japan is indeed weaker than that of the MLB. Not quite as good as the Major Leagues, but a lot tougher than most AAA-level environments, the NPB can be thought of as AAAA+. A pitcher who has gaudy numbers in Japan might not put up such numbers, because of the disparity in overall skill between the MLB and NPB. A hitter who has gaudy numbers in Japan not put up such numbers, because of the disparity in overall skill between the MLB and NPB. Different skill sets are emphasized in the two leagues, as well. The NPB, for example, places less of an emphasis on the home run, and more of an emphasis on small ball. All NPB teams play in stadiums that use artificial turf- as the Mets found out in 2004 when Kaz Matsui was signed, defensive prowess at a position when one is used to artificial turf does not necessarily translate into defensive prowess on grass and dirt. Age is also a factor. The majority of former NPB players who came to the United States to play in the MLB were international free agents, meaning they have their necessary nine years of service time on a team's main roster (where a year is defined as 145 days, which is about four-and-a-half months). If a player makes the main team around age 20 to 24 and stays on it for those nine years consecutively, the earliest he is reaching international free agent status is 29-33. Depending on the length of the contracts they already with their NPB team, and other personal variables, the transition to the MLB can be delayed even further. The fact that most have come in the twilight of their baseball careers, on the wrong side of 30, it can skew expectations of any and all players from Japan, regardless of their age.

Because I prefer pitching over hitting, and because the majority of players who are going to likely be coming to the MLB next season, either via international free agency or via the posting system are going to be pitchers, let's take a look at former NPB pitchers who came to the United States and had careers in the MLB*. Maybe sometime in the future, I'll take a look at hitters.

*A few players who were born in Japan and played baseball in the MLB never actually played in the NPB. That is, for whatever reason, their MLB careers began before their NPB careers did. As a result, I will not look at their careers, since they went through the process backwards (or not at all), and their career numbers in Japan can't be analyzed and compared to that of their career numbers in the MLB, to look at the disparity in performance. These players include Mac Suzuki (moved to the United States from Japan when he was 16, before he could be drafted by an NPB team, and wound up signing a contract with the Seattle Mariners), Michael Nakamura (signed with an MLB team early in his career, and only went to Japan after his opportunities dried up in the U.S.), Kaz Tadano (was blackballed by the NPB for his appearance in a gay porn video- he needed the money, he says, and I am likely to believe him given that he is heterosexual- forcing him to come to the MLB to pursue a career in baseball), and Junichi Tazawa (had designs to play for the MLB since day one, and asked NPB teams not to draft him, so that he could go to the United States).


Kenshin Kawakami


2009: 1.7 WAR

2010: 0.8 WAR

MLB cumulative ERA: 4.32 (41 Starts, 9 Relief Appearances)

NPB cumulative ERA: 3.22 (242 Starts, 15 Relief Appearances)

Hiroki Kuroda


2008: 3.6 WAR

2009: 2.1 WAR

2010: 4.1 WAR

2011: 2.4 WAR

MLB cumulative ERA: 3.45 (114 Starts, 1 Relief Appearance)

NPB cumulative ERA: 3.69 (244 Starts, 27 Relief Appearances)

Hideki Irabu


1997: -0.2 WAR

1998: 1.1 WAR

1999: 2.4 WAR

2000: 0.8 WAR

2001: 0.4 WAR

2002: -0.4 WAR

MLB cumulative ERA: 5.15 (80 Starts, 46 Relief Appearances)

NPB cumulative ERA: 3.47 (159 Starts, 114 Relief Appearances)

Kei Igawa


2007: -0.3 WAR

2008: 0.1 WAR

MLB cumulative ERA: 6.66 (13 Starts, 16 Relief Appearances)

NPB cumulative ERA: 3.15 (179 Starts, 11 Relief Appearances)

Daisuke Matsuzaka


2007: 3.9 WAR

2008: 3.3 WAR

2009: 0.6 WAR

2010: 2.6 WAR

2011: 0.2 WAR

MLB cumulative ERA: 4.25 (105 Starts, 1 Relief Appearance)

NPB cumulative ERA: 2.95 (190 Starts, 14 Relief Appearances)

Hideo Nomo


1995: 4.9 WAR

1996: 3.8 WAR

1997: 3.1 WAR

1998: 1.2 WAR

1999: 2.2 WAR

2000: 2.4 WAR

2001: 3.8 WAR

2002: 2.1 WAR

2003: 2.4 WAR

2004: -0.9 WAR

2005: 0.2 WAR

2008: -0.3 WAR

MLB cumulative ERA: 4.24 (318 Starts, 5 Relief Appearances)

NPB cumulative ERA: 3.15 (134 Starts, 5 Relief Appearances)

Tomo Ohka


1999: 0.0 WAR

2000: 1.2 WAR

2001: 1.5 WAR

2002: 3.4 WAR

2003: 3.0 WAR

2004: 1.0 WAR

2005: 1.6 WAR

2006: 0.7 WAR

2007: -0.1 WAR

2009: -0.8 WAR

MLB cumulative ERA: 4.26 (178 Starts, 24 Relief Appearances)

NPB cumulative ERA: 4.93 (26 Starts, 30 Relief Appearances)

Masato Yoshii


1998: 1.4 WAR

1999: 1.4 WAR

2000: 2.5 WAR

2001: 0.6 WAR

2002: 1.7 WAR

MLB cumulative ERA: 4.62 ERA (118 Starts, 44 Relief Appearances)

NPB cumulative ERA: 3.86 (165 Starts, 220 Relief Appearances)



Kazuo Fukumori


2008: -0.2 WAR

MLB cumulative ERA: 20.25 (0 Starts, 4 Relief Appearances)

NPB cumulative ERA: 3.65 (47 Starts, 367 Relief Appearances)

Shigetoshi Hasegawa


1997: 0.8 WAR

1998: 0.6 WAR

1999: -0.3 WAR

2000: 0.8 WAR

2001: 0.6 WAR

2002: 0.5 WAR

2003: 0.8 WAR

2004: 0.5 WAR

2005: 0.5 WAR

MLB cumulative ERA: 3.71 (8 Starts, 509 Relief Appearances)

NPB cumulative ERA: 3.33 (127 Starts, 15 Relief Appearances)

Ryota Igarashi


2010: -0.3 WAR

2011: 0.0 WAR

MLB cumulative ERA: 5.74 (0 Starts, 74 Relief Appearances)

NPB cumulative ERA: 3.25 (0 Starts, 507 Relief Appearances)

Takashi Kashiwada


1997: -0.4 WAR

MLB cumulative ERA: 4.31 (0 Starts, 35 Relief Appearances)

NPB cumulative ERA: 3.95 (17 Starts, 388 Relief Appearances)

Masao Kida


1999: 0.4

2000: -0.1

2003: 0.3

2004: 0.0

2005: -0.1

MLB cumulative ERA: 5.38 (2 Starts, 65 Relief Appearances)

NPB cumulative ERA: 3.91 (119 Starts, 393 Relief Appearances)

Masahide Kobayashi


2008: 0.1 WAR

2009: -0.1 WAR

MLB cumulative ERA: 5.10 (0 Starts, 67 Relief Appearances)

NPB cumulative ERA: 2.85 (13 starts, 444 Relief Appearances)

Satoru Komiyama


2002: -0.1 WAR

MLB cumulative ERA: 5.61 (0 Starts, 25 Relief Appearances)

NPB cumulative ERA: 3.71 (303 Starts, 152 Relief Appearances)

Masumi Kuwata


2007: -0.8 WAR

MLB cumulative ERA: 9.43 (0 Starts, 19 Relief Appearances)

NPB cumulative ERA: 3.42 (396 Starts, 46 Relief Appearances)

Takahito Nomura


2002: -0.5 WAR

MLB cumulative ERA: 8.56 (0 Starts, 21 Relief Appearances)

NPB cumulative ERA: 3.11 (3 Starts, 335 Relief Appearances)

Hideki Okajima


2007: 1.5 WAR

2008: 1.1 WAR

2009: 0.7 WAR

2010: 0.0 WAR

2011: 0.1 WAR

MLB cumulative ERA: 3.11 ERA (0 Starts, 261 Relief Appearances)

NPB cumulative ERA: 3.36 (38 Starts, 401 Relief Appearances)

Akinori Otsuka


2004: 1.6 WAR

2005: 0.6 WAR

2006: 2.0 WAR

2007: 1.0 WAR

MLB cumulative ERA: 2.44 (0 Starts, 236 Relief Appearances)

NPB cumulative ERA: 2.39 (0 Starts, 305 Relief Appearances)

Takashi Saito


2006: 3.2 WAR

2007: 2.0 WAR

2008: 1.7 WAR

2009: 0.4 WAR

2010: 1.2 WAR

2011: 0.2 WAR

MLB cumulative ERA: 2.18 (0 Starts, 322 Relief Appearances)

NPB cumulative ERA: 3.80 (208 Starts, 131 Relief Appearances)

Kazuhiro Sasaki


2000: 0.7 WAR

2001: 1.7 WAR

2002: 1.6 WAR

2003: 0.4 WAR

MLB cumulative ERA: 3.14 (0 Starts, 228 Relief Appearances)

NPB cumulative ERA: 2.38 (8 Starts, 431 Relief Appearances)

Ken Takahashi


2009: 0.0 WAR

MLB cumulative ERA: 2.96 (0 Starts, 28 Relief Appearances)

NPB cumulative ERA: 4.33 (183 Starts, 276 Relief Appearances)

Hisanori Takahashi


2010: 1.6 WAR

2011: 0.4 WAR

MLB cumulative ERA: 3.55 (12 Starts, 114 Relief Appearances)

NPB cumulative ERA: 3.70 (201 Starts, 44 Relief Appearances)

Shingo Takatsu


2004: 1.0 WAR

2005: -0.8 WAR

MLB cumulative ERA: 3.38 (0 Starts, 99 Relief Appearances)

NPB cumulative ERA: 3.20 (17 Starts, 581 Relief Appearances)

Yoshinori Tateyama


2011: 0.2 WAR

MLB cumulative ERA: 4.50 (0 Starts, 39 Relief Appearances)

NPB cumulative ERA: 3.43 (37 Starts, 401 Relief Appearances)

Koji Uehara


2009: 1.7 WAR

2010: 1.4 WAR

2011: 1.3 WAR

MLB cumulative ERA: 3.13 (12 Starts, 120 Relief Appearances)

NPB cumulative ERA: 3.01 (205 Starts, 71 Relief Appearances)

Keiichi Yabu


2005: 0.0 WAR

2008: 0.4 WAR

MLB cumulative ERA: 4.00 (0 Starts, 100 Relief Appearances)

NPB cumulative ERA: 3.58 (244 Starts, 35 Relief Appearances)

Yasuhiko Yabuta


2008: -0.1 WAR

2009: -0.2 WAR

MLB cumulative ERA: 7.14 (0 Starts, 43 Relief Appearances)

NPB cumulative ERA: 3.97 (93 Starts, 313 Relief Appearances)

(There were too many relievers, a lot of them with too small sample sizes, to bother making a nice graph like I did above with the starters. Sorry.)

Observations and Notes

A few players, after leaving Japan to play in the Major/Minor Leagues, went back to play in Japan- Kazuo Fukumori, Hideki Irabu, Takashi Kashiwada, Masao Kida, Masahide Kobeyashi, Satoru Komiyama, Takahito Nomura, Tomo Ohka, Kazuhiro Sasaki, Ken Takahashi, Shingo Takatsu, Keiichi Yabu, Yasuhiko Yabuta, and Masato Yoshii. Only Kida, Kashiwada, Takatsu, Komiyama, Yasuhiko and Yabuta had any kind of success returning to Japan. Kashiwada is an interesting case, because he returned to Japan at the age of 27.

Many players were of an advanced age when first coming to the U.S., and retired after a relatively short period of baseball activity in North America. Seemingly, this shows that these individuals may have known their baseball lives were at an end, but wanted to ply their trade in the MLB just to get a taste of it, possibly knowing that their services would be of limited upside, at best. I think this, more than anything, skews perceptions about Japanese baseball players (pitchers in particular) not being able to handle the Major Leagues. Tomo Okha is the youngest pitcher to come to America, at age 23, while Ken Takahashi was the oldest, at age 40. The average age of rookie starters is 28.75, while the average age of rookie relievers is 37.16.

By far, Hideo Nomo had the best career of all of the Japanese starters to come to the MLB. His cumulative 24.9 WAR is more than double his nearest competitor, Hiroki Kuroda (12.2 WAR). His longetivity certainly makes his total WAR accumulation look better, but he also has the highest single-season mark, 4.9 WAR, set in his outstanding 1995 rookie season.

The biggest disparities between production in Japan and production in the MLB for starters goes to Hideki Irabu and Kei Igawa- coincidentally, both Yankee signings. Outside of one injury-shortened season, Irabu never posted an ERA over 4.00 in his entire nine-year NPB career before coming to America. In the four years leading up to his ‘trade' to the MLB, his K/9 rate was 10.16/9- his BB/9 rate wasn't nearly as sterling, however. More amazing, however, is the fact that he kept his HR rate really low in Japan- and, by really low, I mean he never allowed a single home run, if the statistics are to be trusted. In the U.S., he gave up the long ball quite frequently, and this might have been the source of his ruin. Though the Yankees overpaid for him, Igawa was coming off of five straight sub-4.00 ERA seasons of 27+ starts (ie, entire seasons), with K/9 rates no lower than 7.50/9 and BB/9 rates no higher than 3.13/9. I will say, I do not think the Yankees gave him a fair chance, after a string of bad performances in 2007, but his Minor League numbers in AA-Trenton and AAA-Scranton have been poor as well outside of one good season in 2008. I'm hesitant to put Dice-K on this list because: (A) Even his worst season wasn't as craptastic as Irabu and Igawa's worst seasons and (B) given how good he was in Japan, it would be hard to replicate that kind of success- if he had a career ERA of 3.50, that would be an entire run higher than his cumulative 2.79 ERA as a starter in Japan when pitching the entire year (I did not factor in his shortened 2002 season).

In terms of judging relievers, it is a bit harder for two reasons: (A) Most of the Japanese pitchers who were relievers in the MLB were starters for a good portion of their baseball careers in the NPB and (B) most of their performances comes in small sample sizes over the course of a few games, over the course of a season or two. All in all, Akinori Otsuka has been the best pure reliever to come from Japan- in the MLB, he appeared in 236 games and had an ERA of 2.44, which is very comparable to his career in the NPB where he appeared in 305 games, and had an ERA of 2.39. Takashi Saito is the best converted reliever to come from Japan- in the MLB, he has appeared in 322 games and has an ERA of 2.18.

The biggest disparities between production in Japan and production in the MLB for a pure reliever goes to Ryota Igarashi. His 74 appearances in the MLB is only a fraction of his 507 in Japan, but the differences in his stats are striking. His 5.74 ERA in the MLB is a great deal higher than his 3.25 career NPB ERA; no two combined years in the NPB is his ERA that high. It looks like he was never really able to adapt to the slightly larger, slightly heavier MLB ball. His worst BB/9 rate in Japan- 5.48, in his rookie season- was about as good as his best BB/9 rate here in America. His K/9 rate is still roughly in line with what it was in Japan, so it seems- and as confirmed by his O-Swing% and O-Contact%- batters were simply swinging and missing at pitches that more or less would have been balls had they not swung.

All in all, Hiroki Kuroda might be the most consistent pitcher to come from Japan. As a starter in Japan, he had a cumulative 3.47 ERA over seven years as a full time starter. In the MLB, he has a cumulative 3.45 ERA over four years. In Japan, he had a cumulative 7.08 K/9 rate over seven years as a full time starter. In the MLB, he has a cumulative 6.71 K/9 rate. In Japan, he had a cumulative 2.04 BB/9 rate over seven years as a full time starter. In the MLB, he has a cumulative 2.07 BB/9 rate. Kuroda has never been too flashy, but he's really one hell of a pitcher. It's criminal, how underrated he is.


I thank for their awesome stat charts that I used- I wouldn't be able to do all of that and stay sane- and's Data Warehouse for historic NPB stat totals.

This FanPost was contributed by a member of the community and was not subject to any vetting or approval process.