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Seattle Mariners Top 20 prospects for 2019

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It is a thin system. . .

Arizona Fall League All Star Game
Evan White
Photo by Christian Petersen/Getty Images

Top 20 Seattle Mariners prospects for 2019

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.


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. 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) Justus Sheffield, LHP, Grade B+: Age 22, over from the New York Yankees in the James Paxton deal, posted 2.48 ERA in 116 innings between Double-A and Triple-A, 123/50 K/BB, just 82 hits and four homers allowed; fastball into mid-90s, effective hard slider but change-up needs more work, as does general command; probably doesn’t have much left to learn in the minors, as his stuff is good enough to succeed in AAA even with remaining flaws; potential number three starter; ETA 2019.

2) Evan White, 1B, Grade B: Age 22, first round pick in 2017 from University of Kentucky, hit .303/.375/.458 with 11 homers, 52 walks, 103 strikeouts in 476 at-bats in High-A; excellent defender at first base; respected for pure hitting skills, controls zone well, game power is behind raw power, future development in that category will determine if he’s just a decent regular or something more; ETA 2020.

3) Logan Gilbert, RHP, Grade B: Age 21, first round pick in 2018 out of Stetson University; posted 2.72 ERA in 112 innings during college season, 163/25 K/BB, 71 hits; didn’t pitch in pro ball; college stats obviously excellent; low-to-mid-90s fastball, mixes in with hard slider, spike curve, and change-up; number three starter package, perhaps more once we get some pro data; ETA 2021.

4) Kyle Lewis, OF, Grade B-: Age 23, first round pick in 2016 out of Mercer; hit .260/.303/.429 in 196 at-bats in High-A then .220/.309/.371 in 132 at-bats in Double-A; career has been slowed by knee injuries and contact concerns; can still look like a future star on the right day but performance against Double-A pitching was disappointing with mixed reports on swing mechanics and approach; let’s give him another year to get past the knee problems; ETA 2020.

5) Julio Rodriguez, OF, Grade B-: Age 17, signed out of Dominican Republic in 2017 for $1,750,000; hit .315/.404/.525 with five homers, 10 steals, 30 walks, 40 strikeouts in 219 at-bats in Dominican Summer League; unusually polished hitter for his age with good feel for the strike zone and plenty of bat speed; should hit for both average and power as he moves up though we need to see him at higher levels than the DSL; speed and arm should fit well in right field; ETA 2022.

6) Dom Thompson-Williams, OF, Grade B-: Age 23, over from the Yankees in the Paxton trade; originally drafted in fifth round in 2016 from University of South Carolina; hit .299/.363/.546 with 22 homers, 20 steals, 33 walks, 102 strikeouts in 368 at-bats between Low-A and High-A; athletic, above-average power and speed potential; will need to see if approach holds up in Double-A to prove that ’18 breakout was real; ETA 2020.

7) Braden Bishop, OF, Grade B-: Age 25, third round pick in 2015 from University of Washington, hit .284/.361/.412 with eight homers, 37 walks, 68 strikeouts in 345 at-bats in Double-A, season ended early due to broken arm; stands out for speed and defense, will flash power but not consistently; looks like prototype fourth outfielder, perhaps more if power maximizes; ETA late 2019.

8) Cal Raleigh, C, Grade B-: Age 22, third round pick from Florida State University in 2018; hit .288/.367/.534 with eight homers, 18 walks, 29 strikeouts in 146 at-bats in Northwest League; switch-hitter with power and good strike zone sense, may not hit for high averages as he moves up but should produce SLG and OBP; defense needs work, has the tools but throwing and receiving marginal at this point; future will depend on glove progress; ETA 2021.

9) Josh Stowers, OF, Grade B-: Age 21, second round pick in 2018 from University of Louisville; hit .260/.380/.4190 with 20 steals, 37 walks, 57 strikeouts in 200 at-bats in Northwest League; ideal leadoff type with speed and patience, has doubles power too; arm may limit him to left field; ETA 2021.

10) Erik Swanson, RHP, Grade C+/B-: Age 25, originally in the Texas Rangers system, traded to Yankees in Carlos Beltran deal then on to Mariners in Paxton trade; solid year in high minors for Yankees, 2.66 ERA in 122 innings, 139/29 K/BB, 93 hits between Double-A and Triple-A; has always thrown strikes but put hitters away more effectively in ’18; low-90s fastball, sometimes higher, mixed with good-enough slider and change-up, number four starter projection. ETA 2019.

11) Jake Fraley, OF, Grade C+/B-: Age 23, comp round pick out of LSU by the Tampa Bay Rays in 2016, traded to Mariners in November Mike Zunino deal; pro career has been slowed by injuries but he hit very well in 2018, .347/.415/.547 in 225 at-bats in High-A, 26 walks, 44 strikeouts, 11 steals; line drive hitter with good speed and doubles power, fourth outfielder projection although could be more if power turns out better than expected; good defender; ETA 2020

12) Sam Carlson, RHP, Grade C+: Age 19, second round pick in 2017 from high school in Minnesota; hurt elbow in spring training, tried to rehab without surgery but eventually had Tommy John surgery in July, will miss 2019 so this will cost him two seasons of development; when healthy features 92-97 MPH heater with potentially plus slider and change-up; ETA ???

13) Noelvi Marte, SS, Grade C+: Age 17, signed out of the Dominican Republic for $1,550,000 in July 2018, hasn’t played yet obviously; scouting reports indicate significant power potential along with one of the more polished bats in the class; has a chance to stick at shortstop although many expect he’ll wind up at third or perhaps right field eventually; we need to see him play before going higher but the reports are promising; ETA ???

14) Joey Curletta, 1B-OF, Grade C+: Age 24, sixth round pick in 2012 by the Los Angeles Dodgers from high school in Arizona, traded to the Phillies in 2016 then to the Mariners in 2017, hit .282/.383/.482 with 23 homers, 81 walks, 130 strikeouts in 465 at-bats in Double-A and was added to the 40-man roster last month to protect him from the Rule 5 draft; big power and has improved command of the strike zone over the last two years; decent glove at first base and can play corner outfield in an emergency; could sneak up on us, don’t overlook; ETA late 2019.

15) Matthew Festa, RHP, Grade C+: Age 25, seventh round pick in 2016 from East Stroudsburg University; posted 2.76 ERA with 20 saves, 67/12 K/BB in 49 innings in Double-A, then pitched 8.1 innings in majors with 2.16 ERA, 4/2 K/BB; classic middle/short reliever with 91-96 MPH fastball, impressive slider, throw strikes; ready soon; ETA 2019.

16) Joey Gerber, RHP. Grade C+: Age 21, eighth round pick in 2018 from University of Illinois; excellent pro debut with 2.10 ERA in 26 innings between Northwest League and Low-A, 43/11 K/BB, eight saves; relief profile similar to Festa with 91-96 MPH fastball, good slider, good control; expected to move through system quickly; ETA 2020.

17) Wyatt Mills, RHP, Grade C+: Age 23, third round pick in 2017 out of Gonzaga, posted 3.57 ERA in 53 innings between High-A and Double-A, 59/13 K/BB, 11 saves; another fastball/slider reliever who throws strikes; Mariners seem to love these guys; ETA 2020.

18) Keegan McGovern, OF, Grade C+: Age 23, ninth round pick in 2018 from University of Georgia; hit .268/.351/.523 with 15 homers, 28 walks, 66 strikeouts in 239 at-bats in Low-A; adapted quickly to pro ball; Midwest League sources liked his power and he could make a lot of noise in the hitter-friendly California League; ETA 2021.

19) Dylan Moore, INF-OF, Grade C+: Age 26, originally drafted by Texas Rangers in seventh round in 2015 from University of Central Florida; signed as minor league free agent by Mariners but was added to 40-man to protect from Rule 5; hit combined .299/.363/.522 with 14 homers, 23 steals, 35 walks, 68 strikeouts in 408 at-bats between Double-A and Triple-A; older prospect at 26 but versatile, has some power and speed, can play every position except catcher and even pitched in one minor league game in 2016; a “sneak up on us” type; ETA 2019.

20) Juan Querecuto, SS, Grade C+: Age 18, signed out of Venezuela in 2017 for $1,225,000; hit .243/.331/.329 in 243 at-bats in the Dominican Summer League; years away but has one of the better physical ceilings in the system; error-prone at shortstop but has the tools to stick there with more reps; bat is projectable, might hit for average with moderate power eventually; ETA 2023.

OTHER GRADE C+ Sam Delaplane, RHP; Eric Filia, OF; Ivan Fortunato, RHP; Nolan Hoffman, RHP; Bobby Honeyman, 3B; Austin Hutchison, RHP; Cesar Izturis, Jr, INF; Luis Liberato, OF; David McKay, RHP; Ian Miller, OF; Max Povse, RHP; Joe Rizzo, 3B; Nick Rumbelow, RHP; Rob Whalen, RHP; Art Warren, RHP; Donnie Walton, INF

OTHERS: Ruben Alaniz, RHP; John Andreoli, OF; Dayeison Arias, RHP; Damon Casetta-Stubbs, RHP; Joe DeCarlo, C; Anthony Jimenez, OF; Michael Koval, RHP; Chris Mariscal, INF Darren McCaughan, RHP; Anthony Misiewicz, LHP; Ljay Newsome, RHP; Joey O’Brien, RHP; Ryne Ogren, SS; Joseph Rosa, 2B; Ronald Rosario, OF; Chuck Taylor, OF; Logan Taylor, 3B-OF

The Mariners system has a reputation as being very thin. The reputation is deserved.

Spots 12 through 20 could be ordered in many different ways with several of the “other C+” guys having a case to be written up. I selected a mixture of bullpen candidates, long-term speculative plays, and possible “sneak up on us” guys for write-ups.

I will answer questions in the comments section and feel free to email comments to for inclusion on the podcast.