Sierra is a legit four-tool talent with an up-the-middle defensive profile, and a chance to grow into a top-of-the-order threat. After struggling in his first taste of full-season ball in 2015 at the ripe old age of 19, Sierra returned to Peoria to start the 2016 season, and he has shown growth in his game across the board. He relies on strong wrists and good feel for the barrel to square up the ball with some regularity, though his overly aggressive approach often leads to empty swings, and leaves him vulnerable to quality secondaries. On the grass, Sierra continues to improve his reads and routes, and looks the part of a future plus defender in center field.

Though he only made one start in the Chiefs’ series in Beloit this week, it was a solid showing that highlighted both the strengths and weaknesses in Sierra’s game. At the plate, Sierra showed an ability to drive the ball the other way on a hard single to left on an elevated fastball, as well as an explosive first step out of the box that earned him an infield hit on a soft grounder to second, and had him clocking 3.9 seconds to reach first base on a jailbreak ground ball that was mishandled by first baseman Ryan Howell.

His aggression was exploited, as well, as Sierra swung at two-thirds of the pitches he saw, struck out chasing, and made soft contact on four of the five balls he put in play, often hitting from behind in the count. On the base paths Sierra moved well, but struggled mightily getting a read on first base, often lunging back to first on pitches to the plate and getting thrown out easily on two stolen base attempts.

Defensively, Sierra shined, tracking down a deeply driven ball and finishing with an over-the-shoulder grab at the wall before spinning and delivering a one-hop throw from the track to the second-base bag. His reads off the bat were clean and his routes efficient. Sierra profiles as a future center fielder that should provide value both in the field and on the bases. His future offensive output comes with a higher degree of potential volatility, however. While he shows good balance at the plate, a feel for contact, and strong wrists capable of spraying the ball to all fields, his bat-to-ball skills are shy of elite, and there is a risk that his aggressive tendencies eat into his hit tool and on-base production. There isn’t much in the way of present or future power, though a more refined approach and improvement in finding balls to drive to the gaps could help Sierra to rack up extra bases thanks to his plus to double-plus speed. The upside is that of a quality top-of-the-order stick, though even as a down-order bat he could grow into an everyday contributor thanks to his glove, arm and legs.