The Around the Horn series, which features a position-by-position look at Oakland's projected starters and backup options heading into the season, shifts to shortstop.
Who's at shortstop?
Marcus Semien enters his fourth season with the A's and, at just 27 years old, is their longest-tenured player. He recently avoided arbitration in his first year of eligibility by coming to terms on a one-year, $3.125 million deal -- a significant bump from his 2017 earnings, which totaled $545,000.
• Around the horn: Lowrie anchors 2B
Semien remains under club control through 2020, and it's unclear whether he's in the A's long-term plans as they build for the future; last spring, the two sides engaged in extension talks, which were tabled when Semien suffered a right wrist injury that later required surgery, which forced him out of action for nearly three months. Sources indicate the conversation never resumed, and Semien said recently, "I just want to focus on playing now."
Offensive outlook
Semien was limited to 85 games last season because of the wrist injury, which hampered his production even after his return. His power was slow to resurface, and Semien settled for 10 home runs on the year -- with four of them coming in his final 11 games, as he continued to reestablish his strength. The shortstop bopped 27 the year before and 15 in 2015, and it's reasonable to envision a season in which he not only totals 25 homers but steals 15 bases.

Semien's stolen base numbers reached double digits in each of his first three seasons with the A's. He was 12-for-13 in his attempts last year, marking his highest total yet. The opportunities will continue to come, with Semien expected to begin the season batting leadoff. He did so on 33 occasions last year, getting on base at a .323 clip from the No. 1 hole.
Overall, Semien's OBP at season's end sat at .325, a career high. Continuing to find different ways on base rather than relying on the long ball -- which was an ongoing theme for these A's in 2017 -- remains Semien's mission. His career average with the A's is .248.
"Everyone likes home runs," Semien said, "but I just want to put together good at-bats. We've got a lot of guys capable of hitting over 20 home runs. We pick our counts, pick our spots. That's what we talk about a lot. Look for a pitch in your zone and let it fly. We can win a lot of ballgames by doing that, but we want to do the little things, too. When our power swing's not there, how do we win a ballgame? We gotta find other ways to execute."
Getting defensive
Semien has dramatically improved his defense since assuming everyday shortstop duties for the A's. Once considered a liability in the field, Semien can hold his own up the middle and is making the routine plays with much greater ease. Given Semien's relentless work ethic, the A's hope they've yet to see the best of him at shortstop, though there's thought he could be even better at second base down the road.
The A's are grooming prospects for both positions, but it's in Semien's power to maintain his job security with continued improvement on the field and sustained production at the plate.

Depth chart
Middle-infield prospects Franklin Barreto and Jorge Mateo will be making a push to crack the big league roster this year, with Barreto the obvious replacement for second baseman Jed Lowrie, who could be dealt midseason before he hits free agency. The speedy Mateo, meanwhile, is expected to play shortstop at Triple-A Nashville. The A's won't rush either player, considering they're quite comfortable with their current middle-infield tandem, but it's a storyline worth watching.