Magneuris Sierra, OF, Miami Marlins

Timed 4.07 and 4.11 up the line from the LHH box; ran a 3.70 flat on a slap ground ball, but already bailing out up the line; 3.78 on a base hit bunt attempt.

Lean and undersized without natural physical strength. Very well-developed forearms and decently strong hands and wrists, but pretty significantly underweight everywhere else through frame; tons of room to grow into his body; scrawny without any power or leverage through core or lower half … Really, really struggling at the plate in my April look; consistently slow bat, firing very late to the ball, almost like he’s not seeing it right; taking bad swings throughout multiple at-bats against multiple different pitchers. Giving away at-bats, even half-swinging; looks checked out and completely over-matched by average fastballs; wonder how much he wants to be there right now. Bad approach; not consistently competitive … Incredible speed when he does actually commit to an at-bat; flies up the line with a very quick first step and almost immediate reach to top speed. That 3.70 time up the line was an eyebrow-raiser, even on a bailout swing; his speed can absolutely change the game when he wants to turn it on … Very inconsistent reads and routes in center field, almost like he had trouble picking the ball up off the bat. Would flash great tracking skills from time to time, and multiple times in my look he tracked down really hard-to-reach balls hit deep into gaps; other times, he struggled to move even a few steps back to read a deep fly ball. Range is clearly there; whether it’s a mindset or focus issue, or a problem picking the ball up off the bat every time, something needs to get sorted out … Enigmatic guy; really tough to figure based on my three-game look; electric natural ability that he seems to be able to turn on at times, but very inconsistent in execution across his game. Really would like to see him play a few more games to get a better read; a very interesting, and maybe polarizing, young prospect.

The general public consensus on Magneuris Sierra is high, and many see him as a key cog for the Miami Marlins and their young nucleus of talented prospects; I saw that guy in flashes, but there’s quite a bit of work to be done here before Sierra has a significant big league impact. Whether it’s a maturity/mental/makeup issue with learning how to take competitive at-bats every time and check-in to every inning, or a physical issue in him needing more time to adjust to Triple-A competition (or a bit of both), Sierra didn’t acquit himself well in my long look this week. He’s struggled mightily to open the season in New Orleans, too — just 4-for-39 with 13 strikeouts in his first nine games. We’ll see how and when he adjusts to right the ship, but this week was not a good first impression for me; must question whether he’s got the capacity for significant big league time any time soon.

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