OAKLAND -- Even home runs in back-to-back games and a walk-off hit Saturday night arent enough to disrupt As manager Bob Melvins platoon system. John Jaso sits today against Nationals left-hander Gio Gonzalez, with Derek Norris catching and Alberto Callaspo getting the start at designated hitter. Washington Nationals pitcher Gio Gonzalez (47) reacts as manager Matt Williams, left, comes to the mound to replace him in the eighth inning of a baseball game against th Philadelphia Phillies, Sunday, May 4, 2014, in Philadelphia.