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Boston Red Sox was the team that Matsuzaka played for in 2008. He joined the Red Sox in 2007 after a successful career in Japan, and quickly became a key member of the team's rotation. In 2008, he made 33 starts and finished with a record of 18-3, an ERA of 2.90, and 219 strikeouts. He was a key contributor to the Red Sox's World Series victory that year.