Part four will draw some conclusions from a big picture level.
Hideki Matsui (OF, Giants -> Yankees): Turned down what would have been the largest contract in NPB history in 2000 (8 years, 6bn yen($60M)) to take a one-year contract, citing his goal of eventually playing in MLB. He eventually did after the 2002 season, and the Giants went from sweeping the Japan Series to finishing in 3rd place (71-66-3). Yomiuri had another 3rd place finish in 2004, then unthinkable consecutive sub-.500 finishes in '05 and '06 before finally recovering in 2007. The Giants made it back to the Japan Series in 2008, six years after Matsui's departure. They had played in four Japan Series' in the 10 years Matsui spent with the team ('94, '96, '00, '02), winning three times. The team's popularity took a hit as well.
So what went wrong? Yomiuri had a pretty weak strategy in replacing Matsui: they signed former Yakult 1st baseman Roberto Petagine and played him in right field, moving Yoshinobu Takahashi to center. Petagine played decent defense at first but was never mobile enough for right field, nor did he have the arm for it. Takahashi said he never felt comfortable in center, and obviously didn't trust Petagine in right.
Things got worse when manager Tatsunori Hara left and was replaced with grouch Tsuneo Horiuchi. The Giants core offensive threats of Kazuhiro Kiyohara, Akira Etoh, Toshihisa Nishi, and Takayuki Shimizu and pitchers Kimiyasu Kudoh, Masumi Kuwata, Yusaku Iriki, and Koji Uehara all became old and/or ineffective at the same time. The team cycled through replacements like Gabe Kapler, Hiroki Kokubo, Tuffy Rhodes, and Jeremy Powell before finally assembling a team that worked in 2007.
Impact:Huge. No single player's departure has had a greater effect on his former team than Matsui has had on the Giants. Yomiuri was probably headed for a downturn anyway, but the loss of Matsui certainly prolonged the team's lean years.
Kazuhisa Ishii (SP, Swallows -> Dodgers): Yakult posted Ishii after winning the Japan Series in 2001, and got about $11m from the Dodgers. Kevin Hodges took Ishii's place at the top of the Swallows' rotation and the team went from a 78-56-6 record in '01 to a 74-62-4 record and 2nd place finish in '02, 11 games behind the Giants. Had Ishii been around, the race might have been tighter but Yakult was still probably would have been a 2nd place team. Hodges posted a 5.90 era in 2004, and Yakult fell further.
Ishii returned to Yakult in 2006, but the team had faded into an also-ran by then. He left after 2007 for Seibu.
Impact: Medium. $11m was a good return for Ishii. Yakult may have been able to remain competitive for a little longer if he had stuck around, but that was an aging team.
So Taguchi (OF, Blue Wave -> Cardinals): Surprisingly, Orix mananged to maintain a solid record the year after Ichiro was posted, but fell from 70-66-4 to 50-87-3 after Taguchi left. Taguchi's presence was never worth 20 games in the standings; the team's offense tanked completely in 2002.
Impact: Low. Taguchi was actually a pretty average player in japan. He really improved his game in his time in America.
Satoru Komiyama (SP/RP, BayStars -> Mets): Yokohama dropped from 69-67-4 to 49-86-5 after Komiyama left. While the 'Stars missed Komiyama's 12-9 record and 3.03 era, I would say that Yokohama's weak offense was more responsible for the team's meteoric drop.
Komiyama didn't perform at the MLB level, and returned to Japan after one season. Yokohama still owned his NPB rights, but refused to sign him to a contract for the 2003 season. After a "ronin" year, the BayStars finally released him and he re-joined the Chiba Lotte Marines, his original team. He's been there ever since.
Impact: Low. Given the way Yokohama treated him, it didn't seem that they wanted him back. They could have traded him to another NPB team and gotten some value back, so to me it was a case of the team cutting off it's nose to spite it's face. In general I'm a fan of Komiyama's and I think he could have added some stability to Yokohama's staff and mentored the team's young pitchers. In that sense, it's a big loss for Yokohama, but not one that I attribute to his MLB trial.
Ichiro (OF, Blue Wave -> Mariners): This one needs no introduction. Orix posted Ichiro after the 2000 and Seattle won his rights with a $14m bid. I was living in Japan at the time, and it was such big, exciting news. It seemed like just announcing his move to MLB made him a bigger star than he already was.
Orix appeared in Japan Series' in 1995 and 1996, but were a .500 team for the last few years of his tenure. The Blue Wave maintained it's .500 record the year after Ichiro was posted, but fell apart in 2002. The team stunk again in 2003, and mid-way through 2004 announced that it would merge with the Kintetsu Buffaloes. The new Orix Buffaloes took the field in 2005 with a group of guys taken in the in the Orix/Kintetsu dispersal draft, and ranged from doormat to also-ran until their surpring 2008 campaign.
Orix's popularity at the gate was flagging even with Ichiro, and his departure didn't make things any better. The team suffered from the inconveniently located Green Stadium Kobe, and the proximity of the popular Hanshin Tigers. The post-merger team plays most of it's home games in Osaka Kyocera Dome, which is a shame because Green Stadium is much nicer and was easily my favorite place to watch a game in Japan. For me, the old Blue Wave had a level of charm that the post-merger team lacks completely.
Impact: Medium. Everyone knew Ichiro was going to America at some point, and Orix did the right thing in posting him. I would argue that Ichiro's MLB success is better for Japanese baseball than if he stayed and broken every NPB record. Orix's competitiveness and popularity took a dive without Ichiro, but this was inevitable.
Tsuyoshi Shinjo (OF, Tigers -> Mets): Shinjo turned down a four-year offer from Hanshin to take a one-year minor league deal from the Mets. The Tigers felt no impact in the win column, going from a 57-78-1 record to 57-80-3. Hanshin backfilled Shinjo by drafting Norihiro Akahoshi, who has been the team's center fielder ever since. Akahoshi has never had any power, but he has better on-base skills than Shinjo ever did and has won multiple Gold Gloves.
As a side note, Shinjo announced his move around the same time as Ichiro did. Though his move was viewed with some skepticism, he proved he could play at the MLB level, which helped inspire a wider range of players to make the jump across the Pacific.
Impact: Low. Hanshin built a balanced team after Shinjo left and has been competitve since 2002. Shinjo held his own at the MLB level, played in the 2002 World Series, and then returned to Japan to help build Nippon Ham into a competitive, popular franchise. I'd say this one worked out well for all parties.
That's it for the player-by-player analysis. Anyone I missed? Anyone disagree with my assessments?