Callaspo to learn as he goes in platoon at first

PHOENIX -- Alberto Callaspo will be the A's first baseman on days the club faces a left-handed starter this season. Manager Bob Melvin confirmed as much Tuesday morning and said he felt confident putting the versatile infielder out there, despite his limited experience at the position.

"He's done some hard work and drills out there," said Melvin, who first mentioned the possibility of such a scenario in the offseason.

This means Brandon Moss and Daric Barton will share time at first base against right-handed starters, though Moss will most likely draw several starts at designated hitter -- at least in the early going. Moss has proved to be a reliable defender at first base, but Barton is still considered better with the glove.

"We're going to play each and every game what we think the best matchup is," Melvin said. "There's different factors -- who's swinging well, and if we have chinks in the armor as far as injuries and so forth. But with us, there's really no set lineup, and that dynamic [at first base] would suggest that, too."

Callaspo had never played first base before this spring, and it remains a work in progress for the 30-year-old, who will also continue to provide a backup option at second and third base.

Callaspo is a career .300 hitter against lefties, reaching base against them at a .346 rate.