Athletics' Vice President & GM Billy Beane announced today that Bob Geren has been relieved of his duties as manager and former Major League manager Bob Melvin has been named interim manager for the remainder of the 2011 season. Geren, 49, was named the A's manager on Nov. 17, 2006. He registered a 334-376 (.470) record in four-plus seasons with Oakland, including a 27-36 mark and last-place standing in the AL West this year. The Diamondbacks' all-time winningest manager, Melvin arrives in Chicago today and will assume his managerial duties tonight when the A's open a four-game series against the White Sox at U.S. Cellular Field.