PEORIA, Ariz. -- Rookie Daniel Vogelbach, who was expected to open the season as Seattle's starting first baseman, instead was optioned to Triple-A Tacoma on Thursday.
The move means veteran Danny Valencia will be Seattle's starter at first base and utility man Taylor Motter can fill in as his backup when needed.
Vogelbach, the team's No. 10 prospect, per MLBPipeline.com, has hit .228/.313/.333 with one homer and five RBIs in 57 at-bats this spring and was in a recent 1-for-24 slump with 10 strikeouts.
• Spring Training:Information | Tickets | Schedule | Gear
"It's been a rough 10-day stretch for him and we just felt at this point, with where he is both offensively and defensively, the best thing for him was to go back and start the season at Tacoma," said general manager Jerry Dipoto. "That doesn't mean he's going to finish the season in Tacoma. But we felt some of the adjustments and work we've asked him to do both defensively and in the batter's box are a lot to expect.
"He put in a lot of work, but as we get closer to Opening Day it became apparent we weren't seeing a product that is finished enough to feel great about starting the season."
Vogelbach was acquired from the Cubs in a trade for Mike Montgomery in July, but Dipoto also acquired Valencia in the offseason to provide an insurance plan that now will go into effect.
"We knew this was a potential outcome," Dipoto said. "We didn't want it to be. But there's a reason we traded for Danny Valencia."
Vogelbach has hit well in the Minor Leagues and the Mariners feel he can be an impact bat at some point. But while devoting considerable energy to his defensive work this spring, the offense has suffered. But Dipoto notes similar paths were taken with several other young Mariners last year who are now critical parts of the team.
"This is very similar to what we did last year with Mike Zunino and James Paxton," he said. "We will take the appropriate time and care to make sure that when [Vogelbach] comes to the big leagues, he's polished enough in the areas that are important."
Valencia also hasn't hit well this spring, batting just .196 in 46 at-bats, but manager Scott Servais notes he has considerable track record at the Major League level.
"You're talking about somebody with six or seven years in the big leagues vs. somebody with 30 at-bats," he said.