Getting to Know: Magneuris Sierra: Can He Thrive After His Unexpected Promotion?

by Eric Stashin (aka The Rotoprofessor)

The Cardinals’ outfield has been hammered by injuries over the past few days, leading to the surprising promotion of Magneuris Sierra directly from High-A.  It’s not to say that the 21-year old doesn’t have the ability, but with just 81 AB above Single-A it’s easy to wonder if he’s going to quickly be overmatched by the aggressive promotion.  With that in mind, let’s get to know him a little bit better and see where his upside lies:

Rotoprofessor Rankings:
Preseason – Cardinals’ #5 prospect

Hits – Leftt-Handed

Age – 21

2016/2017 Statistics:

2016 (Single-A)524.3073607831
2017 (High-A)81.27209163

What We Said:
Sierra spent the season at Single-A, hitting .307 with 31 SB.  Listed at 5’11” and 160 lbs., obviously he’s never going to profile as a power hitter.  Instead he could develop as your prototypical top of the order bat, utilizing his top-end speed to make things happen.  He does need to make some adjustments at the plate, as he needs to draw more walks (3.9%) to fit the profile.  At 20-years old (he’ll turn 21 in April), he does have time to get there.

So much for having the time to figure it out, though he was showing more of an ability to take a walk prior to his recall (7.9% at High-A).  Of course that’s not a lot, and it also came in a very small sample size, so we have to take it with a bit of a grain of salt.  Throw in that he hadn’t walked in his last nine games at High-A, you can tell that it’s still a significant work in progress.

He also wasn’t being very efficient on the base paths, going 3-for-8 in stolen base attempts.  He’s also never going to hit for much power, given his stature and 63.1% groundball rate while at High-A.  That’s not a bad thing, given that his speed is his carrying tool, but he needs to be able to draw walks and get on base for the profile to play up.  With a 10.8% line drive rate, that doesn’t appear primed to be the case.

It’s easy to envision this first stay in the Majors being a short one, and while he’s here he could easily be overmatched.  He has potential and could still develop, but his first month of the season at High-A did little to answer our concerns.  He needs more time to develop, and being thrust into a Major League lineup probably isn’t the answer.  Maybe he has a little hot streak, but ultimately MLB pitchers will expose him.

Current Grade – B
Upside Grade – B+

Sources –, Fangraphs

Make sure to check out all of our 2017 Prospect Rankings:

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  1. Edgar says:

    Hi Prof,
    So I finally have someone willing to trade, but I’m trying to dial in a fair deal for both of us. 12-team roto league, no dynasty and I’m in first, but trying to build a team that will compete throughout the season. Here’s the offer on the table (that the other player’s made):

    Me: Posey, Gio Gonzalez, Brach, Castillanos
    Him: Realmuto, Bumgarner, Harrison (Pit), and Souza

    First, thought? Here’s the rest of my team.

    Position players:
    Freeman, Altuve, Rendon, Andrus, Bautista, Belt, Bellinger, Carpenter, Hernandez (2, PHI), Inciarte, V. Martinez

    Sale, Keuchel, Carrasco, Leake, Giles (RP), Robertson (RP), with Paxton, Kluber, Nola, and Jon Gray on the DL.

    I think I’m going to flip Martinez for Moncada.

    I was thinking about countering asking for Donaldson (instead of Harrison & Souza) to see if he’s interested.


    Thank you as always!

    • Rotoprofessor says:

      The problem is not sure when you are going to get anything from Bumgarner. I’d definitely at least ask about Donaldson, though I doubt he bites at that. It never hurts and would definitely make it a better deal

      • Edgar says:

        Thanks Prof,
        I’m guessing after the all-star break, but you’re right, just never know. Thankfully there are two DL slots.

        Would you stay put then or pull the trigger if he said yes to Donaldson?

      • Edgar says:

        Okay, he rejected the addition of Donaldson…

        • Rotoprofessor says:

          Not surprised, but worth a shot. It’s tough to predict when Moncada is going to be up, which makes dropping one of them for him tricky, but he’s well worth stashing

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