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Seattle Mariners Top 20 prospects for 2016

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Edwin Diaz
Edwin Diaz
Nat Thomas, Jackson Generals

Seattle Mariners Top 20 Prospects for 2016

The list and grades are a blending of present performance and long-term potential. Comments are welcome, but in the end all analysis and responsibility is mine. Full reports on all of players can be found in the 2016 Baseball Prospect Book. We are now taking pre-orders for the book, so order early and order often!

All of these grades are preliminary and subject to change.


Grade A prospects are the elite. In theory, they have a good chance of becoming stars or superstars. Theoretically, most Grade A prospects develop into stars or at least major league regulars, if injuries or other problems don’t intervene. Note that is a major "if" in some cases.

Grade B prospects have a good chance to enjoy successful careers. Some will develop into stars, some will not. Most end up spending several years in the majors, at the very least in a marginal role.

Grade C prospects are the most common type. These are guys who have something positive going for them, but who may have a question mark or three, or who are just too far away from the majors to get an accurate feel for. A few Grade C guys, especially at the lower levels, do develop into stars. Many end up as role players or bench guys. Some don’t make it at all.

Finally, keep in mind that all grades are shorthand. You have to read the full comment in the book for the full analysis about a player, the letter grade only tells you so much. A Grade C prospect in rookie ball could end up being very impressive, while a Grade C prospect in Triple-A is likely just a future role player.

1) Edwin Diaz, RHP, Grade B: Age 21, posted 4.57 ERA with 103/37 K/BB in 104 innings in Double-A; ERA was deceptive, FIP was much better at 3.22; fastball at 93-97 with peaks at 98, slider and change-up have steadily improved, both solid-average at least and slider may be plus; control good, potential mid-rotation starter. Do not underestimate him.

2) Alex Jackson, OF, Grade B/B-:
Age 20, first round pick in 2014 was supposed to be a polished power hitter but has not lived up to pre-draft press clippings; 60-grade power but hitting approach very raw, hit just .157/.240/.213 in 108 Low-A at-bats, then .239/.365/.466 with 61 strikeouts in 163 at-bats after moving down to Northwest League. Most sources still rank him as the top prospect in the system but at this point I prefer Diaz. Jackson still offers big offensive upside and is young enough to solve his contact and plate discipline issues, but these issues weren’t supposed to be there in the first place.

3) Drew Jackson, SS, Grade B-/B:
Age 22, hit .358/.432/.447 with 30 walks, 35 strikeouts, 47 steals in 226 at-bats in Northwest League; fifth round pick out of Stanford had stunning debut; has always had strong tools including 60/65 speed and 70-arm but didn’t hit much before last year; swing tweaks and emphasis on plate discipline vaulted him forward. Solid defender can stick at short; future leadoff man if he keeps hitting like this. Could be Top 100 prospect six months from now if he maintains this momentum, maybe even Top 50.

4) Tyler O’Neill, OF, Grade B-/B:
Age 20, hit .260/.316/.558 with 32 homers, 29 walks, 137 strikeouts in 407 at-bats in High-A; showed better plate discipline late in the year; hit .286/.361/.659 with 19 walks in final 49 games; no question about power, all a matter of approach, several hitters in the system have similar issues.

5) Nick Neidert, RHP, Grade B-:
Age 19, second round pick in 2015 from high school in Georgia, successful debut with 1.53 ERA, 23/9 K/BB in 35 innings, 92-95 MPH fastball from athletic 6-1, 180 frame; both curveball and change-up can be above-average with more development, already throws strikes; number four starter potential at least and perhaps a number three.

6) Andrew Moore, RHP, Grade C+/B-:
Age 21, competitive balance pick out of Oregon State, exceptional command/control, posted 2.08 ERA with stunning 43/2 K/BB in 39 innings in Northwest League; best pitch is change-up, fastball at 88-92 but plays up due to command; breaking stuff draws mediocre reviews but I think it may be under-rated; limited physical upside but hard to match his feel for pitching.

7) Luiz Gohara, LHP, Grade C+:
Age 19, big 6-3, 210 lefty from Brazil with fastball up to 95, slider varies from plus to poor, change-up needs work, posted 5.54 ERA with 67/38 K/BB in 63 innings, 77 hits between Northwest League and Low-A. Very raw, more thrower than pitcher right now, high upside, high risk, could turn into number two starter or a total bust. Years away.

8) Boog Powell, OF, Grade C+:
Age 23, hit .295/.385/.392 in Double-A/Triple-A in Rays system, traded to Mariners in Brad Miller/Logan Morrison deal, ideal fourth outfielder type with speed, good strike zone judgment, defense, not much home run power. Some think he might hit enough to start but I think bench role is more likely.

9) Ryan Yarbrough, LHP, Grade C+:
Age 24, fourth round pick from Old Dominion in 2014, posted 4.10 ERA with 88/23 K/BB in 97 innings between High-A and some rookie ball rehab work after a groin injury; threw 87-89 in college but up to 92-94 as a pro thanks to mechanical improvements, above-average change-up, average breaking ball, throws strikes, fourth starter projection.

10) Nick Wells, LHP, Grade C+:
Age 20, ultra-projection lefty (6-5, 185) acquired from Blue Jays in Mark Lowe trade, posted 3.42 ERA with 47/15 K/BB in 50 innings in short-season ball, just 36 hits, fastball around 91 should get faster as he fills out, already has good curveball and workable change-up, throws strikes, loose. Mid-rotation potential, do not overlook him.

11) Tony Zych, RHP, Grade C+:
Age 25, posted 2.98 ERA with 55/8 K/BB in 48 innings in Double-A/Triple-A; 2.45 ERA with 24/3 K/BB in 18 innings in majors, former prospect in Cubs system struggled with Chicago but was much more effective after being sold to Seattle; fastball in mid-90s, plus slider, will be effective as long as he throws strikes.

12) Dan Altavilla, RHP, Grade C+:
Age 23, posted 4.07 ERA with 134/53 K/BB in 148 innings in High-A; stocky 5-11, 200 pound build, lively 93-95 MPH fastball, good slider, potential fourth starter or middle reliever; fifth round pick in 2014 from Mercyhurst University.

13) Austin Wilson, OF, Grade C+:
Age 24, hit .239/.342/.374 with 10 homers, 31 walks, 115 strikeouts in 380 at-bats in High-A. Looks bad, but hit great in second half: .290/.393/.452, big offensive potential in 6-4, 250 body but size leads to contact issues; can he make adjustments in Double-A?

14) Braden Bishop, OF, Grade C+:
Age 22, third round pick from University of Washington in 2015, hit .320/.367/.393 with five walks, 33 strikeouts, 13 steals in 219 at-bats in Northwest League; excellent fielding in center field with instincts, range; 65-70 speed; big question is strike zone judgment as he moves up. Could be regular if he adapts and develops more pop; could also fit as fourth/fifth outfielder.

15) Jio Orozco, RHP, Grade C+:
Age 18, 14th round pick from Arizona high school in 2015; posted 2.95 ERA with 24/4 K/BB in 21 innings in rookie ball; very advanced, mature body at 6-1, 210 but already throws 90-94, curve and change-up very good for his age; good feel for his craft as well. Limited physical projection but already has quality stuff.

16) Dylan Thompson, RHP, Grade C+:
Age 19, fourth round pick in 2015 from high school in South Carolina, 2.36 ERA with 25/8 K/BB in 26 innings in rookie ball, 18 hits; more physically projectable than Orozco but breaking ball and change-up are not as refined; both could be mid-rotation starters.

17) Cody Mobley, RHP, Grade C+:
Age 19, posted 1.71 ERA in 26 innings in rookie ball, 19/10 K/BB; eighth round pick in 2015 from high school in Indiana; part of nice group of high school arms selected in the ’15 draft by Mariners; 6-3, 190 and athletic; fastball at 90-94; already has very good curveball. Like Thompson and Orozco, could develop into mid-rotation arm.

18) D.J. Peterson, 1B, Grade C+:
First round pick in 2013; hit .223/.287/.344 with seven homers, 31 walks, 93 strikeouts in 372 at-bats in Double-A/Triple-A; season ended early with Achilles injury; very disappointing season; unable to duplicate big power production in college and 2014; reports indicate his swing fell apart. Several Mariners prospects had similar issues; be interesting to see if this changes with new front office.

19) Paul Fry, LHP, Grade C+:
Age 23, posted 2.03 ERA with 113/24 K/BB in 80 innings between High-A and Double-A; 68 hits; excellent stats on the season; low-90s fastball with movement; good slider and average change-up; 17th round pick in 2013 could be fine middle reliever.

20) Luis Liberato, OF, Grade C+:
Age 20, Dominican Republic signee in 2012; hit .260/.341/.453 with five homers, 24 walks, 47 strikeouts, 10 steals in 181 at-bats in Northwest League; interesting combination of slightly above average power and speed; rather raw but has a chance to develop into multi-tool regular.

OTHERS OF NOTE: Greifer Andrade, SS; Jonathan Aro, RHP; Rayder Ascanio, INF; Jacob Brentz, LHP; Mayckol Guaipe, RHP; Guillermo Heredia, OF; Brayan Hernandez, OF; Tyler Marlette, C; Gareth Morgan, OF; Tyler Pike, LHP; Dario Pizzano, OF; Tyler Smith, SS; Christopher Torres, SS

In the Mariners discussion thread, a reader joked about just giving everyone a C+ and moving on. I didn’t do that on purpose, but I might as well have.

I will post some player book comments in the thread below.