Top 10 Prospects (2016): Seattle Mariners: Is There Any Upside In A Struggling System?

by Eric Stashin (aka The Rotoprofessor)

The Mariners system lacks that true elite talent, though there are players (at least one of them) who have the potential to get to that level.  At the same time it’s hard to consider this a particularly impressive farm system right now, though there are players who could make an impact as soon as 2016.  Who has the most upside?  Who could make a quick impact?  Let’s take a look:

1) Alex Jackson – Outfielder
ETA – 2018
Grade – B+

The grade probably should be higher but a miserable 2015 campaign, including a bloated strikeout rate (28.9% at Single-A, 31.0% at Low-A), has got to make us at least a little bit skeptical.  He played all of 2015 at 19-years old and battled through injuries, the latter of which easily could have impacted his production.  At one point he was in the conversation for the first overall pick in 2014 (he ultimately was selected sixth overall), so there is obvious upside potential and could help ease the concerns this past season created.

The question is going to be how long it takes him to refine his game, especially his contact rate.  Those types of numbers at the lower levels are eye popping, especially since expectations are for them to rise against more advanced pitching.  There is power in his bat (11 doubles, 1 triple, 8 home runs over 163 AB at Low-A), something that should continue to grow and develop.  Still, as we’ve seen with the Rangers’ Joey Gallo if you can’t make contact the power isn’t going to matter much.

2) Edwin Diaz – Right-Handed Pitcher
ETA – 2016
Grade – B+ (borderline B)

Diaz started the year at High-A (37.0 IP), but spent most of the season at Double-A (104.1 IP).  The 4.57 ERA and 1.33 WHIP would imply some struggles, but a 64.8% strand rate and .333 BABIP shows that poor luck played a role.  He showed strikeouts (8.88 K/9) and control (3.19 BB/9), while he’s also showed the ability to generate groundballs (0.97 GO/AO).  He’s clearly still developing, but the upside is there.  We’d like to see him add some weight (he’s listed at 6’3” and 165 lbs.), but don’t be surprised to see him make his debut at some point this season.

3) Luiz Gohara – Right-Handed Pitcher
ETA – 2018
Grade – B

A year ago Gohara was being discussed in the same breath as the Dodgers’ Julio Urias, but the wheels have fallen off a bit since he was promoted to Low-A.  Just look at the walk rates over the past two seasons:

  • 2014 (37.1 IP) – 5.79
  • 2015 (53.2 IP) – 5.37

He has continued to generate strikeouts (67 K over 63.1 IP in ’15) and groundballs (2.26 GO/AO in the minors) while the gaudy ERA (8.20 & 6.20) have at least been partly due to poor luck (strand rates of 48.1% and 59.6%).  At 19-years old he has plenty of time to develop as the stuff is there.  Hopefully he can refine his control, because the upside is there to develop into a mid-rotation option (at worst).

4) Patrick Kivlehan – First Baseman/Third Baseman/Outfielder
ETA – 2016
Grade – B

Most people go to D.J. Peterson first, but it’s Kivlehan that likely will get the first opportunity when needed.  Spending ’15 at Triple-A he hit .256 with 22 HR and 14 SB over 472 AB.  He had 20 HR and 11 SB over 519 AB in ’14, so we can’t simply chalk it up to spending the year in the Pacific Coast League.  A 21.8% strikeout rate is solid and he also didn’t benefit from a strong BABIP (.289).  A football player in college, he only played baseball as a senior, he’s still learning and developing but the potential is obviously there.

5) Tyler O’Neill – Outfielder
ETA – 2018
Grade – B-

He spent the bulk of the season at High-A, slugging 32 HR with 16 SB over 407 AB.  That’s going to grab our attention, but a 30.5% strikeout rate vs. a 6.5% walk rate is a significant red flag.  He’s relatively inexperienced, so we have to afford him time to mature and learn on the fly.  That said there’s obviously significant risk involved given that type of strikeout rate at such a low level.

The Next Five:

6) D.J. Peterson – First Baseman/Thirdbaseman
7) Ryan Yarbough – Left-Handed Pitcher
8) Andrew Moore – Right-Handed Pitcher
9) Luis Liberato – Outfielder
10) Nick Neidhart – Right-Handed Pitcher

Sources –,, Fangraphs, Baseball Reference

Grading System (still in development):
Grade A – Elite Prospects (aka potential future perennial All-Stars)
Grade B – Above Average Prospects (aka above average Major Leaguers, could develop into a potential All-Star)
Grade C – Average Prospects (aka solid, though unspectacular)
Grade D – Nothing More Than Roster Filler
Grade F – Move On

Make sure to check out all of our Top 10 Prospect Lists:

AL EastAL CentralAL West
Baltimore OriolesChicago White SoxHouston Astros
Boston Red SoxCleveland IndiansLos Angeles Angels
New York YankeesDetroit TigersOakland A's
Tampa Bay RaysKansas City RoyalsSeattle Mariners
Toronto Blue JaysMinnesota TwinsTexas Rangers
NL EastNL CentralNL West
Atlanta BravesChicago CubsArizona Diamondbacks
Miami MarlinsCincinnati RedsColorado Rockies
New York MetsMilwaukee BrewersLos Angeles Dodgers
Philadelphia PhilliesPittsburgh PiratesSan Diego Padres
Washington NationalsSt. Louis CardinalsSan Francisco Giants


  1. The Colonel says:

    What grade would you give Ketel Marte?

    • Rotoprofessor says:

      I’d probably put him in the B/B- range. There is potential, especially in the SB, but he’s not going to be an All-Star.

      I’m actually going to be covering him on the baseball site in the next few days!

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