Around the Horn: Who's on first for A's?

The multipart Around the Horn series, which features a position-by-position look at Oakland's projected starters and backup options heading into the season, begins at first base.
Who's on first?
The A's opted to hang on to Yonder Alonso and sign the 29-year-old to a one-year, $4 million deal for the 2017 season. That lines Alonso up to return as Oakland's everyday first baseman, though several other names remain in play as options to spell him -- including Mark Canha.
Then there's Matt Olson, ranked by MLB.com as the club's No. 16 prospect. Olson enjoyed the proverbial cup of coffee in September and, though his prospect star has perhaps diminished of late, he still profiles as a traditional power hitter with impressive defensive skills at the position, making him a potential long-term everyday possibility.

Offensive outlook
The A's would like to see Alonso improve offensively in his second season in Oakland, but he's never been known to serve up the kind of production at the plate that teams crave from a corner infielder. His career average sits at .269, after he hit .253 in a career-high 156 games in 2016. Alonso's slugging percentage (.367) and OPS (.683) both ranked fourth lowest in the American League, and he hit just seven home runs. He hasn't compiled more than seven homers since 2012, when he totaled a career-high nine with the Padres.
Power resides elsewhere, though, in Oakland's secondary options. Canha, who could see some at-bats at first when not in right field as a right-handed-hitting platoon option, hit 16 home runs as a rookie in 2015. He then managed only 16 games in '16 -- with three long balls -- before undergoing season-ending hip surgery.
Getting defensive
Advanced defensive metrics weren't kind to Alonso in 2016, but it's fair to consider them outliers in an otherwise positive career that has seen his teammates and employers rave about his glove. Alonso's ability to scoop would-be throwing miscues made him a favorite among teammates -- particularly shortstop Marcus Semien, whose decreased error total can be partially credited to Alonso.
Depth chart
The A's have several other fill-in options on their roster: catcher Stephen Vogt is one of them, as is third baseman Ryon Healy, who could potentially see more time here in the future upon No. 4 prospect Matt Chapman's arrival in the Majors at the hot corner. Keep an eye on Olson, meanwhile, as the kid attempts to make a competition out of camp.