After Davis went deep in the fifth, catcher Bruce Maxwell followed with his first home run of the season to give Oakland a 7-0 lead. Jed Lowrie also had a pair of RBIs with a first-inning double in his 2-for-4 night for the A's (38-48).
Valencia unloaded a three-run homer in the ninth to cut the final margin, but the Mariners (41-46) dropped their eighth straight home game, their longest losing streak at Safeco Field since May 2010. Shortstop Jean Segura went 4-for-4 with a double to hike his average to .