The A’s suffered their second winless homestand of the season at 0-5.
Jaime Barría limited the A’s to an unearned run in three innings of relief to pick up his first win since May 8.
The teams traded runs in the 10th inning, with Sierra and Ramón Laureano producing RBI singles. Austin Pruitt gave up Sierra’s deciding double. The Angels took a 3-0 lead in the sixth on a three-run homer by Luis Rengifo, his seventh of the year. Oakland tied it in the seventh on a three-run double by Tony Kemp, who was thrown out at third trying to stretch it to a triple.
Both Sears and Stevenson are new to the A’s and made their debuts in part because of a pair of roster moves the A’s made before the game: All-Star Paul Blackburn was originally scheduled to start the series finale, but he was placed on the IL with inflammation in his right middle finger. Stevenson was promoted when veteran Jed Lowrie was designated for assignment, ending the 38-year-old’s third stint in Oakland.