(CBS) The Cubs have lost another key member of manager Joe Maddon’s coaching staff.

Bench coach Davey Martinez has reached an agreement to become the Nationals’ manager, 670 The Score confirmed Sunday morning. The deal is for three years with an option for a fourth year, a source said.

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The deal was first reported by the Washington Post.

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Martinez, 53, has served as Maddon’s bench coach for the past 10 seasons, the first seven in Tampa Bay and the last three in Chicago. He’s widely respected throughout the game for his knowledge and relationships with players.

The Nationals’ managerial job opened up when they chose not to renew Dusty Baker’s contract last week despite him leading Washington to a pair of division titles in his lone two seasons there. The Cubs eliminated the Nationals in five games in the National League Divisional Series.

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Martinez is the fifth member of the Cubs’ staff to leave since season’s end, joining pitching coach Chris Bosio, hitting coach John Mallee, assistant hitting coach Eric Hinske and third-base coach Gary Jones. Jim Hickey has agreed to a deal to become the Cubs’ new pitching coach, though it hasn’t been announced. Chili Davis has been hired as the new hitting coach, while Brian Butterfield will take over as third-base coach. Andy Haines was promoted internally to assistant hitting coach.