The A’s promoted Triple-A Nashville manager Ryan Christenson to the big-league staff. He’ll be manager Bob Melvin’s bench coach. Christenson, 43, managed in the A’s system the past five years including 2015 and 2016 when he led Double-A Midland to Texas League championships. He was bumped to Nashville in 2017. His teams posted a collective .561 winning percentage (391-307), and he managed many of the players who broke into the majors in the past year including Matt Olson, Matt Chapman, Ryon Healy, Bruce Maxwell and Chad Pinder. Christenson replaced Chip Hale, who’ll be the third-base coach.