This is the fourth of a multipart Around the Horn series that features a position-by-position look at the A's projected starters and backup options heading into the 2017 season. Previously: 2B | 1B | C
Who's at shortstop?
Marcus Semien made good on the A's decision to stick with him at shortstop in 2016, upping his game all around to lock down the everyday job. Semien's defensive progress under the watch of since-departed infield whiz Ron Washington was well-documented, and Semien also began fulfilling his offensive potential by busting out for 27 home runs, 12 more than he totaled with nearly as many at-bats in 2015.
Offensive outlook
In the early going of his A's tenure, Semien's bat was often overshadowed by his glove, which drew attention for the wrong reasons. But he has since emerged as one of the better power-hitting shortstops in the game. Semien's 27 home runs tied Colorado's Trevor Story for most in the Majors among shortstops, increasing his total to 42 over the last two years -- most in the Majors at the position in that span.
Moving forward, Semien, a lifelong student of the game, would like to improve further as a hitter, pointing to his overall batting average (.238 in 2016) and on-base percentage (.300).
Getting defensive
Semien came into his own as a shortstop in 2016, just one year removed from a dismal season marked by 35 errors, an A's record. That number fell to 21 last year, and though tied for the Major League lead among shortstops, it reflected a drastic improvement. Semien, whose tireless work ethic cannot be overstated, made better throws and bobbled fewer balls, and his progress is only expected to continue.
Not to be overlooked is Semien's durability. He played in all but three games in 2016, missing those for the birth of his son.
Depth chart
Semien is firmly entrenched at shortstop, but it's no secret that the A's top prospect plays the same position.

Franklin Barreto, who was considered the key piece in the 2014 Josh Donaldson trade despite being just 18 years old at the time, is not far off from being deemed Major League ready. Barreto, now 20, has spent the majority of his professional career at shortstop, but he's also logged time at second base, which will perhaps quicken his journey to the Majors.