Magneuris Sierra: Marlin on the Rise

Magneuris Sierra is the only Miami Marlins prospect who has experience playing against the Marlins at the major league level. That experience came May 8-10, 2017 at Marlins Park, Sierra’s first full series following his initial call-up. The Dominican outfielder didn’t seem the least bit intimidated: 5-for-11 (.455 BA), 6 R, 2 BB while playing every inning in a St. Louis Cardinals sweep.

Sierra’s speed proved to be a deciding factor in the middle game. With one out in the ninth inning, AJ Ramos rushed the throw to first on his grounder back to the mound, moving the eventual winning run into scoring position:

That wasn’t an isolated incident. Watch him carve up Trevor Williams and the Pittsburgh Pirates on July 16 without even hitting a ball out of the infield:

Even as a 21-year-old, Sierra had a meaningful impact on the outcome of MLB games. He arrived as the third-youngest player in the league behind only Julio Urias and Luis Torrens, per Baseball-Reference (until several fresher faces showed up during the second half of the season).

Especially after witnessing that first hand, we can understand why the Marlins considered him a worthy return in the Marcell Ozuna trade. The haul of prospects also included Sandy Alcantara, Daniel Castano and Zac Gallen (who we recently profiled).

Rather than GIF through every other moment of Sierra’s summer, the stats can further illustrate his unique skill set. First, from Baseball Savant:

Notice the asterisk? Although Sierra was recalled by the Cardinals four separate times last season, he played only 22 games for them. Overall, he batted .317/.359/.317 with zero extra-base hits and two stolen bases, plus some notable defensive plays.

Despite flashes of brilliance, there remain concerns about the Marlins’ best position player prospect (in MLB Pipeline’s estimation). Drilling down into his minor league production reveals inconsistencies in Sierra’s performance since he turned pro in 2012.

He earned widespread acclaim two years after signing with St. Louis. At age 18, Sierra dominated the Gulf Coast rookie league: .386/.434/.505 (170 wRC+), 2 HR, 13 SB in 52 games. Playing regularly in center field, he demonstrated good contact skills and ran the bases efficiently. It earned him 2014 Cardinals Minor League Player of the Year honors as the youngest ever recipient of the award (h/t Viva El Birdos).

However, that peak was sandwiched between two much more ordinary offensive showings at other rookie levels (115 wRC+ in 2013 Dominican Summer League; 117 wRC+ in 2015 Appalachian League).

Sierra’s success relies on reaching base because he has barely developed any power. He set a career high with four home runs in 2015, but failed to match that in either season since, despite participating in 122 and 101 regular season games in 2016 and 2017, respectively. Only a handful of his 64 plate appearances with the Cardinals resulted in legitimate fly balls, none of which would’ve reached the Marlins Park warning track.

Source: Baseball Savant

Reigning AL MVP Jose Altuve has spoiled all of us—he is the exception, not the norm. It’s unrealistic to tip the scales at 160 pounds (Sierra’s listed weight) and mash baseballs with authority. Players built like that typically need to optimize all their other skills to compensate for a key deficiency.

Sierra could still try to emulate an established MLB All-Star, but rather than Altuve, how about the recently dealt Dee Gordon?

Photo by Mike Ehrmann/Getty Images

Their measurables—from size to Sprint Speed—are eerily similar. Yet without ever learning to slug, Gordon has “made it.” He’s been the National League’s batting title winner, Gold Glover, Silver Slugger and stolen base leader before turning 30, amassing an average of 3.8 fWAR during his three full major league campaigns (2014, 2015, 2017). That might be the ceiling for Sierra, but it should be worth waiting for.

Somebody better tell the Marlins! MLB.com’s Joe Frisaro points out how Christian Yelich, Braxton Lee and Sierra are the only three conventional outfielders on Miami’s entire 40-man roster. At least the club has invited J.B. Shuck and Rafael Ortega to spring training on minor league deals. Internal options like Garrett Cooper, Derek Dietrich and Martin Prado all have some outfield background, too. Plenty of potential stopgaps.

Sierra already showed that he can survive on an active roster, but the Marlins don’t need to force it. Ideally, he’ll spend much of 2018 refining his game against opponents closer to his own age, likely for the Triple-A New Orleans Baby Cakes (a level he skipped last season on his expedited journey to the majors).

Barring severe injury, Sierra should be swimming with the Fish this September.