Masahiro Tanaka, the 25-year-old Japanese right-hander who was 24-0 for the Rakuten Golden Eagles last season, has agreed to a seven-year, $155 million contract with the New York Yankees, sources said Wednesday morning.

As part of the new rules governing the system that allows Japanese players to sign with a U.S. club, the Yankees will pay an additional $20 million to Rakuten. Tanaka can opt out of the contract after four years.

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For $175 million, then, the Yankees sign the best starting pitcher in a thin free-agent market. Due to his 53-9 record over the past three seasons, an ERA in that time well under two, a clever split-fingered fastball and his youth, Tanaka is perhaps the most hyped pitcher to come from Japan since Hideki Irabu (to the Yankees) more than 15 years ago. Many scouts believe he will be somewhat less effective, however, than Yu Darvish, who in the past two seasons with the Texas Rangers is 29-18 and has become the ace of that staff.

Tanaka had drawn heavy interest from across the game. The Los Angeles DodgersChicago Cubs,Arizona Diamondbacks and Chicago White Sox, along with the Yankees, were especially involved. He had 30 days – until Friday – to sign with a U.S. team, and in that time met with several clubs in Los Angeles.

Known in Japan by the nickname “Ma-kun,” Tanaka is a veteran of Olympic and World Baseball Classic competition. He has twice led Nippon Professional Baseball in wins, ERA and complete games, and in 2011 led the league in strikeouts. Also, he has twice been named the league’s top starting pitcher.

Still, the transition to the U.S. game has been difficult for some well-regarded Japanese pitchers. And while Tanaka seeks to follow in the footsteps of Hideo Nomo, Hiroki Kuroda and Darvish, there is a risk he will not adapt. Daisuke Matsuzaka had one exceptional season for the Boston Red Sox. He cost the Red Sox more than $100 million in posting fees and salary. The Yankees spent more than $46 million on Kei Igawa in 2006. He won two big-league games. Irabu, who signed a $12.8 million contract with the Yankees (after being traded from the San Diego Padres) before the current posting system was developed, never seemed comfortable with the U.S. game and retired with a losing record.

The Yankees are betting Tanaka has the talent and temperament to stand at or near the top of their rotation. While he lacks the power of Darvish, Tanaka does throw a fastball in the mid-90s. He has an uncommonly good split-fingered fastball and an effective slider. Tanaka threw significant innings as a young pitcher – 186 1/3 as an 18-year-old and a career-high 226 1/3 at 22 – and often threw more pitches than his U.S. counterparts, though that seems of little concern to most scouts.

The Yankees, while counting their dollars against the luxury tax, were the favorites to land Tanaka, in part because of their financial wherewithal and in part because their starting rotation is so thin.

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