Seattle made the surprising roster move Thursday. Vogelbach, a left-handed hitter, and Valencia, who bats right-handed, had been expected to split time at first depending on pitching matchups. But Vogelbach has struggled in spring training, hitting just .228 and will now start the season in the minors.
Vogelbach appeared in just eight games for the Mariners late in the 2016 season. At Triple-A last season, Vogelbach hit .292 with 23 home runs and 96 RBI in 133 total games.
Valencia, another offseason acquisition by Seattle, hit .275 against right-handed pitching last season with Oakland.
Taylor Motter will be the backup at first base.