A’s designate team leader Stephen Vogt for assignment Vogt, a two-time All-Star and a fan favorite, was the undisputed team leader, but he was batting .217 with four homers and 20 RBIs in 54 games. [...] Oakland placed third baseman Matt Chapman on the 10-day DL with left knee cellulitis and called up first baseman-outfielder Matt Olson and Bruce Maxwell. The A’s fired pitching coach Curt Young last week and designated free-agent acquisition Trevor Plouffe for assignment before trading him to Tampa Bay.