BOSTON -- Mark Kotsay, who became a valuable member of the Red Sox following a late-season trade, has filed for free agency.
Kotsay became a vital member of the Sox in the postseason, particularly when third baseman Mike Lowell had to end his season because of ongoing right hip woes.
Kevin Youkilis moved across the diamond to take over for Lowell while Kotsay was inserted into the lineup at first base. Despite playing the outfield for the majority of his career, Kotsay did an excellent job at first.
Because of his desire to be a starter, Kotsay is likely to prioritize places other than Boston during his stay on the free-agent market.
But if Kotsay can't find anything that appeals to him, Red Sox general manager Theo Epstein has already been on record as saying the club would have interest in bringing him back.
Epstein acquired Kotsay from the Braves in a waiver trade on Aug. 27. After hitting .289 with six homers and 37 RBIs in 88 games with Atlanta, Kotsay hit .226 with 12 RBIs in 22 games for Boston.
His two-out double in eighth inning of Game 5 of the American League Championship Series set up Coco Crisp for a game-tying single in a game the Red Sox trailed 7-0 entering the bottom of the seventh. The Sox went on to win the game but lost the ALCS in seven games to the Tampa Bay Rays.
Kotsay joined Jason Varitek, Curt Schilling, Bartolo Colon, Sean Casey, Alex Cora and David Ross as players from the Red Sox who have filed for free agency.
Veteran pitchers Mike Timlin and Paul Byrd are the only eligible players from the Red Sox who have yet to file for free agency. There's a strong chance that Timlin will retire.
Ian Browne is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.