The 2015 Seattle Mariners Top 10 Prospects

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For an explanation on the CAL, the Comparison And Likeness prospect classification system I derived, click here.



1.  Alex Jackson, LF/RF

Born: 12/25/95  Age: 19   Height: 6-2   Weight: 215   B/T: R/R                                                        
Top CALs: N/A
2014 18 R 96 .274 .337 .464 .801 0.190 9.4% 27.1% 124

Background: The second prep bat taken last June, the Mariners wasted little time moving Jackson from behind the plate – the position he starred at while playing for powerhouse Rancho Bernardo HS. Fun fact: among those that have walked through the school’s hallways are Cole Hamels and Hank Blalock. The organization pushed Jackson down to the lowest rung, the Arizona Summer League, where he offered plenty of offensive promise. He batted .280/.344/.476 with six doubles, two triples, and two homeruns while posting a 129 wRC+.

Projection: Widely regarded as the top power prep bat in last year’s class. Jackson offered up a solid eye, borderline red flag contact issues and plenty of power during his incredibly short debut. Very, very limited sample size.

Ceiling: Too Soon to Tell

Risk:  N/A




2.  D.J. Peterson, 1B/3B

Born: 12/31/91  Age: 23   Height: 6-1   Weight: 190   B/T: R/R                                                        
Top CALs: Nick Evans, Christian Marrero, Josh Bell, Ryan Braun, Jerry Sands
2013 21 A- 123 .312 .382 .532 .914 .220 10.6% 14.6% 162
2013 21 A 107 .293 .346 .576 .922 .283 6.5% 22.4% 155
2014 22 A+ 299 .326 .381 .615 .997 .289 7.7% 21.7% 154
2014 22 AA 248 .261 .335 .473 .808 .212 8.9% 20.6% 126

Background: Initially spurning the organization’s attempts to lure him into professional baseball, the Mariners, who drafted the 6-foot-1 corner infielder in the 33rd round coming out of high school, finally got their man three years later when they grabbed him with the 12th overall pick. Peterson, the older brother of Braves prospect Dustin, enjoyed his collegiate days playing in the bandbox that is Lobo Baseball Field. He batted a robust .317/.354/.545 with 41 extra-base hits, which earned him nods from the NCBWA and Louisville Slugger as a Freshman All-American. Peterson raised the bar during his follow up campaign – he slugged .419/.482/.734 with 21 doubles, three triples, and 17 homeruns – and was recognized by Louisville Slugger as a First Team All-American as well as being named the Mountain West Co-Player of the Year and semifinalist for the Golden Spikes Award. And then he upped the ante even further during his junior year. Appearing in 55 games for the Lobos, Peterson batted .408/.504/.807 with 25 homeruns, four triples, and a career best 18 homeruns.

Since entering pro ball two years ago Peterson has proven that concerns about his inflated offensive production were unfounded. He hit .303/.365/.553 between Everett and Clinton during his debut, and then put together a .297/.360/.552 with 31 doubles and 31 homeruns between the California and Southern Leagues last season.

Projection: Prior to the 2013 draft I wrote,

“The problem with Peterson’s production is that most of it has been done in a bandbox. And once his [numbers] are adjusted for park and schedule (according to, his overall line, while solid, is noticeably less (.364/.487/.739). In fact, his adjusted wOBA, .475, fell to #6.”

I continued,

“Peterson is a solid big league prospect, probably being nabbed somewhere in the middle to back half of the first round. He’s always shown a strong eye at the plate and his power grades out as a 55 or 60.”

I also described Peterson as having a ceiling as a .280/.350/.500-type hitter with 25-HR potential.

Nearly two years in and it still sounds about right. Peterson obviously benefited from spending time with High Desert – his park adjusted triple-slash line is .299/.355/.543 according to – but he still managed to top the Class AA average production by 26%. Average plate discipline with a surprising modest K-rate and above-average pop. Defensively, he loses either way – he brings a sieve to the hot corner and as a first baseman he won’t provide much value.

Ceiling:  3.0- to 3.5-win player

Risk:  Moderate

MLB ETA:  Late 2015/Early 2016



3.  Tyler Marlette, C

Born: 01/23/93  Age: 22   Height: 5-11   Weight: 195   B/T: R/R                                                        
Top CALs: J.R. Murphy, Ryan Casteel, Luis Exposito, Gary Sanchez, Travis D’Arnaud
2012 19 R 214 .284 .304 .423 .727 .139 2.8% 21.5% 100
2013 20 A 297 .304 .367 .448 .815 .144 8.1% 17.8% 132
2014 21 A+ 339 .301 .351 .519 .870 .218 7.1% 18.0% 123
2014 21 AA 36 .250 .333 .500 .833 .250 11.1% 27.8% 132

Background: A fifth round pick out of Hagerty HS, home to Phillies top prospect Zach Efflin, in 2011, Marlette’s slow offensive simmer is nearing a boiling point. After hitting .284/.304/.423 in the Appalachian League three years ago, the stout backstop followed that up with a .304/.367/.448 mark in the Midwest League in 2013. Promoted to the High Desert bandbox, Marlette, unsurprisingly, feasted off of the High Class A pitching – he slugged .301/.351/.519 with 23 doubles and 15 homeruns while posting a 132 wRC+ in 81 games. The organization bumped him up to the Southern League for a quick nine-game crash course.

Projection: Tremendously underrated throughout the industry, even his park adjusted stats with High Desert remain strong: .280/.330/.465 ( Solid average power with the chance to peak somewhere in the neighborhood of 17 or so homeruns, a decent eye at the plate, and better than average hit tool, Marlette has a chance to develop into a solid everyday backstop. Defensively speaking, he’s still a work in progress – he coughed up 22 passed balls in 81 games – but managed to effectively control the running game (35% CS%).

Ceiling: 2.5- to 3.0-win player

Risk:  Moderate

MLB ETA:  2016



4.  Edwin Diaz, RHP

Born: 03/22/94  Age: 21   Height: 6-2   Weight: 178   B/T: R/R                                                        
Top CALs: Joseph Cruz, Castillo Perez, Frank Lopez, Mitchell Taylor, Yanery Vasquez
YEAR Age Level IP ERA FIP K/9 K% BB/9 BB% HR/9 LOB%
2012 18 R 19.0 5.21 7.11 9.5 22.2% 8.1 18.9% 0.95 67.3%
2013 19 R 69.0 1.43 3.04 10.3 30.4% 2.4 6.9% 0.65 88.3%
2014 20 A 116.3 3.33 3.48 8.6 23.0% 3.3 8.7% 0.39 69.5%

Background: Seattle has been slowly bringing around the 2012 third round pick. After a very…questionable…debut in the Arizona Summer League in 2012 – he posted a 20-to-17 strikeout-to-walk ratio in 19.0 innings – Diaz began to shine in the Appalachian League in 2013. In 13 starts with Pulaski, the 6-foot-2 right-hander fanned 79, walked 18, and posted a 3.04 FIP in 69.0 innings. The organization moved him into the Midwest League last season and he continued to perform well against older competition: 116.1 innings, 23.0% K%, 8.7%, and 3.48 FIP.

Projection: Ignoring the putrid debut three years ago, Diaz has quietly been one of the system’s better young arms. Better than average control, promising strikeout rates, and he not only handled the move into full season well, but the average age was nearly two years his senior.

Ceiling:  2.5-win player

Risk:  Moderate

MLB ETA:  Late 2017/Early 2018



5.  Ji-Man Choi, 1B/LF

Born: 05/19/91  Age: 23   Height: 6-1   Weight: 225   B/T: L/R                                                        
Top CALs: Yonder Alonso, Logan Morrison, Max Muncy, Mitch Moreland, Billy Butler
2012 21 A 294 .298 .420 .463 .883 .165 13.3% 18.7% 151
2013 22 A+ 211 .337 .427 .619 1.045 .282 12.8% 15.6% 169
2013 22 AA 236 .268 .377 .485 .862 .217 13.6% 11.9% 150
2014 23 AAA 281 .283 .381 .392 .774 .110 12.8% 14.9% 108

Background: Choi’s long been on my radar as a type of sabermetric superhero, or at the very least a really badass sidekick. An unheralded signing out of Korea, Choi entered his professional debut in the Arizona Summer League with little fanfare but left it 39 games later and jumped straight up to High Desert and finished the year with a combined .360/.440/.517. He missed the entire 2011 season recovering from a back injury – I’m sure pushing him behind the plate for the first time the previous year didn’t help – and was bounced down to the Midwest League, where he would string together a nice 60-game stretch in 2012.

The following year, 2013, Choi was moved back to the California League and, unsurprisingly, experienced an offensive explosion – he batted .337/.427/.619 with a 169 wRC+ in 48 games, numbers that remain impressive after adjusting for High Desert’s bandbox (.318/.409/.572). The club would push him up to Jackson for 61 games (.268/.377/.485) before having the lefty-swinging first baseman spend the final 13 contests in the PCL. Overall, Choi finished the year with a combined .295/.394/.535 with 36 doubles, six triples, and 18 homeruns.

Needless to say, I was incredibly high on him heading into 2014. I ranked him as the 130th overall prospect while noting in mid-2013, “Choi [has] a ceiling residing somewhere close to 3.0-wins.” And then the wheels, while they didn’t all fall off, came pretty damn close last season.

Choi opened the year up on a tear, hitting .394/.500/.545 during his first nine games, and then he got popped for the performance-enhancing drug methandienone and was suspended for 50 games. After a quick four-game refresher with Jackson, Choi hit .265/.361/.368 the rest of the way with Tacoma.

Projection: As damning as this might sound, there was a point not too long ago that Choi looked like the second coming of Daric Barton – the good one. Choi’s always walked a ton in his career, over 13% of the time, while showing surprising power, though it hasn’t translated into homeruns. Choi’s sporting a career .183 ISO, but slugged just 34 homeruns in 312 games which, believe it or not, could play surprisingly well at Safeco. Cal’s fairly optimistic in terms of extracting big league value by linking him to three league average bats – Logan Morrison, Mitch Moreland, and Yonder Alonso – and Billy Butler.

Ceiling:  2.0- to 2.5-win player

Risk:  Low to Moderate

MLB ETA:  2015



6.  Austin Wilson, LF/RF

Born: 02/07/92  Age: 23   Height: 6-4   Weight: 249   B/T: R/R                                                        
Top CALs: Miguel Velasquez, Luke Tendler, Chris Swauger, Jeremy Synan, Jonathan Burnette
2013 21 A- 226 .241 .319 .414 .732 .172 7.5% 18.6% 114
2014 22 A 299 .291 .376 .517 .893 .226 8.7% 21.7% 153

Background: A tool-laden outfielder out of Stanford, Wilson never really dominated at any point during his three-year collegiate career. As a true freshman – and former 12th round pick by the Cardinals – Wilson held his own while playing in the PAC12 (then known as the PAC10): he hit .309/.330/.420, but slugged only 11 extra-base hits and sported an atrocious 56-to-7 strikeout-to-walk ratio. He did take a pretty big developmental leap forward during his sophomore campaign, improving his strikeout-to-walk ratio to a more respectable 44-to-24 while hitting .285/.352/.493. Combined with his work in the Cape Cod that summer, Wilson headed into his final year with more than a few accolades: Preseason First Team All-America (Perfect Game, Baseball America), Preseason Second Team All-America (Louisville Slugger), and Golden Spikes Award Watch List. A stress reaction in his elbow, however, would limit him to just 31 games during his final year.

Seattle grabbed the 6-foot-4, 249-pound corner outfielder in the second round last summer and sent him directly into the Northwest League, where he batted .241/.319/.414. The club pushed him up to the Midwest League last season, where a strained Achilles tendon limited him to just 72 games. He hit .291/.376/.517 with 32 extra-base hits.

Projection: His pre-draft analysis:

“He’s well-built, but he’s never really shown a whole lot of power. And for a player relegated to a corner outfield spot that’s a bit concerning. He’s more about projectability right now, maybe with 20/20 potential. He might be what Oakland’s Michael Taylor was supposed to be, but there’s more risk than normal.”

He obviously looks the part. And he manhandled the competition last season. But he’s coming from an elite baseball program playing in the lowest level of full season ball. Wilson might never run enough to swipe 20 bags, but the power potential is there. Solid, slightly better-than-average ceiling.

Ceiling:  2.0 to 2.5-win player

Risk:  Moderate

MLB ETA:  2017



7.  Luiz Gohara, LHP

Born: 07/31/96  Age: 18   Height: 6-3   Weight: 210   B/T: L/L                                                        
Top CALs: Michael Feliz, Dean Aldridge, Erik Manoah, Doug Salinas, Clayton Cook
YEAR Age Level IP ERA FIP K/9 K% BB/9 BB% HR/9 LOB%
2013 16 R 21.7 4.15 3.06 11.2 27.6% 3.7 9.2% 0.42 60.1%
2014 17 R 12.7 2.13 1.98 11.4 31.4% 1.4 3.9% 0.00 69.2%
2014 17 A- 37.3 8.20 6.26 8.9 19.8% 5.8 12.8% 1.45 48.1%

Background: Depending upon your specific religious views Gohara’s aggregate ERA last season could be an omen of things to come. The 6-foot-3 man-child made a pair of ridiculously dominant starts in the Arizona Summer League – he punched out 16, walked two, and allowed three earned runs in 12.2 innings – the organization bumped him up to the Northwest League, where he missed nearly a bat per inning but was hampered by some problematic control.

Projection: Gohara’s tallied just 71.2 innings during his two pro seasons so, obviously, the data set is incredibly limited. But he has averaged 10 strikeouts per nine innings with decent control – especially for a player who’s yet to turn 18. CAL offers up some optimism by tying him to Michael Feliz, but the big southpaw is basically a complete unknown.

Ceiling:  Too Soon to Tell

Risk:  N/A




8.  Carson Smith, RHP

Born: 10/19/89  Age: 25   Height: 6-6   Weight: 215   B/T: R/R                                                        
Top CALs: Manny Parra, Dan Straily, Ian Kennedy, Henry Barrera, Josh Ellis
YEAR Age Level IP ERA FIP K/9 K% BB/9 BB% HR/9 LOB%
2012 22 A+ 62.0 2.90 3.35 11.2 28.4% 4.1 10.3% 0.29 77.2%
2013 23 AA 50.0 1.80 1.65 12.8 35.0% 3.1 8.4% 0.18 80.2%
2014 24 AAA 43.0 2.93 2.89 9.4 24.7% 2.7 7.1% 0.21 68.9%

Background: Ugh…Seattle, you’re totally doing it wrong. Coming off of a season in which he posted a tidy 1.99 ERA with a 129-to-48 strikeout-to-walk ratio, the Mariners grabbed the Texas State ace in the eighth round and immediately pushed him into the bullpen. It’s sort of the anti-Cincinnati mantra. For their part, Smith has been rather dominant during his fast track to the big leagues. He’s averaged over 11 strikeouts and just 3.4 walks per nine innings in his three-year career in the minors. Seattle called him up once the rosters expanded to 40 and the big 6-foot-6 right-hander tossed 8.1 scoreless innings.

Projection: Why not give Smith at least half of a year to see if he can stick in the rotation? Where’s the harm in that? Smith showed off a low- to mid-90s fastball, which plays up given his height, during his debut and complemented it with a hard slurvy-type slider. He’s always missed a lot bats and his control has been improving. High leverage power-armed reliever.

Ceiling:  1.5-win player

Risk:  Low to Moderate

MLB ETA:  Debuted in 2014



9.  Victor Sanchez, RHP

Born: 01/30/95  Age: 20   Height: 6-0   Weight: 255   B/T: R/R                                                        
Top CALs: Edgar Garcia, Stolmy Pimentel, Jacob Turner, Deolis Guerra, Alex Sanabia
YEAR Age Level IP ERA FIP K/9 K% BB/9 BB% HR/9 LOB%
2012 17 A- 85.0 3.18 3.77 7.3 19.7% 2.9 7.7% 0.53 69.7%
2013 18 A 113.3 2.78 3.01 6.3 16.9% 1.4 3.9% 0.32 70.5%
2014 19 AA 124.7 4.19 4.39 7.0 18.2% 2.5 6.4% 1.23 70.9%

Background: As an organization, the Mariners have never been shy about aggressively pushing highly talented young prospects through the system. After all, Felix Hernandez made his big league debut before his 20th birthday. And while Sanchez isn’t nearly as talented as King Felix, the front office continued to challenge him in 2014. After making his debut in the Northwest League as a 17-year-old, Sanchez handled his foray into full season with aplomb the following season. Not wanting to send him to the bandbox known as High Desert, Sanchez bypassed High Class A and headed straight for Jackson last season.

In 23 starts, the rotund right-hander posted a solid 97-to-34 strikeout-to-walk ratio in a career high 124.1 innings to go along with his 4.39 FIP. For his career, the 6-foot, 255-pound Sanchez has averaged 6.8 punch outs and 2.2 walks per nine innings.

Projection: Rotund is putting it kindly. Sanchez weighs what offensive linemen used to weigh 50 years ago. Ignoring the fact that he has the distinct possibility to go all Calvin Pickering and eat himself out of baseball, Sanchez looks like a solid backend starting pitcher. He’s certainly not overpowering, but shows guile beyond his years. Control is his best – and nearly only – asset.

Ceiling: 1.5- to 2.0-win player

Risk:  Moderate to High

MLB ETA:  Late 2016/Early 2017



10.  Gabriel Guerrero, RF

Born: 12/11/93  Age: 21   Height: 6-3   Weight: 190   B/T: R/R                                                        
Top CALs: Henry Ramos, Jay Austin, Quincy Latimore, Cesar Puello, Reid Engel
2012 18 R 225 .355 .409 .605 1.014 0.250 9.3% 12.4% 179
2012 18 R 80 .333 .350 .560 .910 0.227 3.8% 16.3% 130
2013 19 A 499 .271 .303 .358 .661 0.087 4.2% 22.6% 85
2014 20 A+ 580 .307 .347 .467 .814 0.160 5.9% 22.6% 110

Background: Guerrero’s taken the Jekyll-and-Hyde approach to open up his professional career – alternating between poor and strong performances on a yearly basis. The evil Edward Hyde showed up during his debut in the Dominican Summer League (.236/.288/.298), followed by the emergence of Henry Jekyll in 2012 (.349/.393/.593). But that sonofabitch Jekyll revealed himself two years ago in the Midwest League (.271/.303/.358 with an 85 wRC+) before being (temporarily?) pushed back to the depth in 2014. The 6-foot-3, 190-pound Dominican-born outfielder took full advantage of his time in The Desert last season, hitting .307/.347/.467 with career highs in doubles (28) and homeruns (18) while topping the league average production by 10%.

Projection: Another one of the younger prospects being thrust through the system at a rapid rate. Outside of his 2012 stint in the DSL, Guerrero’s never really walked a whole lot. He’ll flash surprising power and it could be a repeatable above-average skill down the road as he fills out. Fringy big league everyday potential.

Ceiling:  1.5-win player

Risk:  Moderate

MLB ETA:  2017



**All Statistics Courtesy of FanGraphs**


After serving as a video scout/analyst for Baseball Info Solutions, Joe Werner began writing at his original site, He’s since transitioned into his current niche, prospect analysis, at He has been fortunate — and incredibly blessed — to have some of his work published and mentioned by several major media outlets, including: ESPN, and the Baseball Research Journal. He can be reached at: