To me, the trend of NPB stars moving to MLB has meant more jobs for Japanese players and more opportunities for exchange. For others, it's signified a decline in Japanese baseball. But let's take a look at how each player's move to MLB has affected the teams involved.
Player movement is a part of the business of baseball, and while there's a general trend of Japanese players wanting to test their skills in MLB, each situation is a little bit different. We've seen players ranging from role players like Hideki Okajima and So Taguchi to Hall of Fame-caliber stars like Ichiro and Daisuke Matsuzaka make the move over. We've MLB departures go unnoticed, and have a huge impact on a team's fanbase. So let's examine each case and see what the impact has been overall.
Hiroki Kuroda (SP, Carp -> Dodgers): Despite losing both Kuroda and star 1st baseman Takahiro Arai (Hanshin) to free agency, Hiroshima still managed to improve from 5th place (60-82-2) in 2007 to 4th (69-70-5) in 2008. Of course, if the Carp had been able to hang on to either one of those guys, they probably would have beat out Chunichi for the last playoff spot. Still, Colby Lewis did an outstanding job taking over for Kuroda as the ace, and the team looks primed to make a step forward in it's new stadium.
Impact: Medium. Losing Kuroda probably kept the Carp out of the playoffs in '08, but the team still improved on it's record. Hiroshima is a small market and losing free agents domestically been a reality for the Carp for years.
Kosuke Fukudome (RF, Dragons -> Cubs): Chunichi won the Japan Series in 2007 despite Fukudome missing significant time due to injuries. The Dragons signed veteran slugger Kazuhiro Wada to take Fukudome's place in the lineup, surrendering reliever Shinya Okamoto the Lions as compensation. Wada had a solid year (.302/.345/.475) but Chunichi fell from 2nd to 3rd place, and lost out to the Giants in the playoffs.
Impact: High. Wada is an above-average hitter but lacks Fukudome's defensive skills, and cost the Dragons some bullpen depth. Chunichi looks set for a step back next season with Kenshin Kawakami and Norihiro Nakamura out the door as well. The team continues to draw well though.
Masa Kobayashi (RP, Marines -> Indians)Yasuhiko Yabuta (RP, Marines -> Royals): Soichi Fujita (Yomiuri) departed as well, breaking up Lotte's "YFK" relief combination. The Marines dropped from 2nd place in 2007 (76-61-7) to 4th (73-70-1) in 2008. Bullpen performance may have played a role in the increase in losses (six fewer ties compared to 2007), but Bobby Valentine still had four relievers who posted an era of 3.05 or lower.
Impact: Low. Bullpens fluctuate, and on paper Lotte managed to replace the performance they got out of Yabuta and Kobayashi.
Kazuo Fukumori (RP, Eagles -> Rangers): Rakuten seemed ready to compete for a playoff spot for most of 2008, but wound up finishing one game out of last despite outscoring their opponents by 20 runs. A return to form from Fukumori would have helped, but this was a guy that posted a 4.75 ERA in 2007.
Impact: Minimal. Fukumori was expendable coming off a bad season.
Daisuke Matsuzaka (SP, Lions -> Red Sox): Obviously a huge loss for the Lions, as they went from 2nd (80-54-2) to 5th (66-76-2). Jason Johnson was signed to replace Matsuzaka in the rotation, but was more interested in hanging out in Roppongi and never panned out. Hideaki Wakui, on the other hand, established himself as an ace, and the team rebounded in 2008 to win the Japan Series. Seibu used the $51M they received for Matsuzaka to make some stadium improvements, but otherwise hasn't changed the way they run the team.
Impact: Medium. Everyone knew Matsuzaka was going to MLB, and Seibu got the maximum return by hanging on to Matsuzaka for as long as they could. Despite popularity problems, Seibu has always found ways to win.
Hideki Okajima (RP, Fighters -> Red Sox): Nippon Ham lost some bullpen depth when Okajima left, but still managed to make it to their 2nd consecutive Japan Series in 2007. The Fighters acquired Okajima for a couple of very spare parts so they basically got a free year out of him.
Impact: Low. Losing Michihiro Ogasawara (Yomiuri) and Tsuyoshi Shinjo (retirement) has had a bigger affect on Nippon Ham's competitiveness. I wold suggest that Trey Hillman's departure to MLB had a bigger impact on the Fighters than Okajima's.
Kei Igawa (SP, Tigers -> Yankees): Igawa went 14-9 in 2006 as Hanshin finished 2nd to Chunichi with an 84-58-4 record. Without him in 2007, Hanshin dropped to 74-66-4 and a 3rd place finish. In addition to the loss of Igawa, Hanshin's other starters took a step back in 2007, with Tsuyoshi Shimoyanagi leading the team in innings pitched with just 129 1/3. Igawa's departure also coincided with the Tigers' offense regressing, as Tomoaki Kanemoto, Andy Sheets, Akihiro Yano and Osamu Hamanaka all performing significantly worse than the previous season.
The rotation improved 2008, with Minoru Iwata stepping into a more prominent role. The offense improved as well, and Hanshin led the Central League comfortably for most of the year before choking down the stretch to finish 2nd.
Impact: Medium. Igawa was the only significant personel change, and the team finished 10 wins worse in 2007 than in 2006. Hanshin recovered in 2008 though, and the loss of Igawa never affected the team at the gate. Igawa was inconsistent for his last three seasons in Japan, but the Tigers still haven't found an innings eater to take his place. Looking back though, Hanshin definitely sold high on Igawa and got a nice infusion of cash back for him without sacrificing on long-term competitiveness.
Akinori Iwamura (3B, Swallows -> Rays): Yakult replaced Iwamura on the field with Aaron Guiel, and saw it's record go from 70-73-3 in '06 to 60-84-0 in '07. It wasn't Guiel that cost the team 10 wins, as he posted an .874 OPS compared to Iwamura's .933 mark in '06. Guiel dsappeared in '08 as the Swallows rebounded slightly to 66-74-4.
Impact: High. Short-term, the impact of losing Iwamura probably wasn't that great. By the time Iwamura was sold to the Rays, most of the Swallows stars from the team's mid-90's glory years were gone or fading, and the team was heading into a period of decline anyway. Yakult has a star to build around in Norichika Aoki, but losing Iwamura has certainly slowed their return to competitiveness.
Masumi Kuwata (SP, Giants -> Pirates): The Giants had banished Kuwata to the farm team for all of 2006 and didn't notice he was gone. Kuwata, meanwhile, had a great "nothing to lose" attitude during his time with the Pirates.
Impact: None, except making the Giants look bad for unceremoniously dropping another veteran.
Agree? Disagree? Any information I haven't presented here?
I'll look at players that moved from 2000-2006 in parts 2 and 3 of this series.