The 2016 Seattle Mariners Top 10 Prospects

Announcement: After peaking as the #3 book among all baseball books on Amazon last year, my new book, The 2016 Prospect Digest Handbook, is on sale! Check it out here!

And for those wondering what CALs are, here’s an article on the Comparison And Likeness program I designed.




1. Edwin Diaz, RHP                                                          
Born: 03/22/94 Age: 22 Bats: R Top CALs: Randall Delgado, Luke Jackson,

Eduardo Rodriguez, Jordan Walden, Johnny Barbato

Height: 6-3 Weight: 165 Throws: R

YEAR Age Level IP W L ERA FIP K/9 BB/9 K% BB% HR/9 LOB%
2013 19 R 69.0 5 2 1.43 3.04 10.30 2.35 30.4% 6.9% 0.65 88.3%
2014 20 A 116.3 6 8 3.33 3.48 8.59 3.25 23.0% 8.7% 0.39 69.5%
2015 21 A+ 37.0 2 0 1.70 3.62 10.22 2.19 29.8% 6.4% 0.73 90.6%
2015 21 AA 104.3 5 10 4.57 3.22 8.88 3.19 23.3% 8.4% 0.43 64.8%

Background: After unleashing Felix Hernandez to wreak havoc on the baseball world more than a decade ago – yes, it’s really been that long – Seattle followed that up with the long awaited arrival of Taijuan Walker, another big hard-throwing right-hander a couple years ago. And it appears that Diaz could be the next in line to ascend to the big league throne to complete the triumvirate of dominance. Tall enough to look his future rotation-mates squarely in the eyes, Diaz, who stands a wiry 6-foot-3 and 165 pounds, shook off a horrible debut in the Arizona Summer League five years ago and has been quickly moving through the system’s minor league ladder. He torched the Appalachian League, more than held his own – and some might say sparkled – as he moved up to the Midwest League two years ago, dominated – briefly – with Bakersfield, and posted a strikeout-to-walk ratio in the 3-to-1 neighborhood in Class last season.

Diaz, whom I named as one of the Top 25 Breakout Prospects for 2015, was simply breathtaking in his opening seven starts last season – all coming in the California League. He would toss 37.0 innings while fanning 42 and walking just nine to go along with a 1.70 ERA. The Seattle front office would bounce him up to the minors’ toughest challenge, Class AA, in mid-May for another 20 starts. Throwing 104.1 innings with the Jackson Generals, Diaz would fan 23.3% and walk 8.4% of the batters he faced. And he was particularly dominant over his final 12 starts with the club: 61.2 IP, 65 K, and 19 BB.

Overall, Diaz would finish the year with an aggregate 3.82 ERA in a career high 141.1 innings, tallying 145 strikeouts and just 46 walks.

Projection: There’s really nothing poor to say when it comes to Diaz – he’s tall and projectable (still), has been missing a ton of bats and continues to do so as he rapidly advances through the system, has succeeded against much older competition, and his control has been trending in the right direction since posting a near one-to-one strikeout-to-walk ratio during his brief pro debut. And CAL seems to be a particularly big fan of the young right-hander as well, comparing him to a lot of hard-throwing, high-strikeout relievers in Luke Jackson, Jordan Walden, and Johnny Barbato. He might not have the ceiling of Walker, but Diaz has the potential to settle in nicely as a rock-solid #3-type arm.

Ceiling: 3.0-win player

Risk: Low to Moderate

MLB ETA: 2016/2017


2. Alex Jackson, LF/RF                                                   
Born: 12/25/95 Age: 20 Bats: R Top CALs: Jose Dore, Kyler Burke,

Phillips Castillo, Roberto Rodriguez, Guillermo Pimentel

Height: 6-2 Weight: 215 Throws: R

2015 19 A- 197 11 1 8 0.239 0.365 0.466 0.227 10.7% 31.0% 140
2015 19 A 121 6 0 0 0.157 0.240 0.213 0.056 5.0% 28.9% 37

Background: Sandwiched between Nick Gordon and Aaron Nola as the sixth selection in the draft two years ago, the Rancho Bernardo product was widely recognized as the prep power bat in that year’s class. And after signing on the dotted line for more than $4 million dollars, it didn’t take long for the backstop-turned-corner-outfielder to display his prodigious pop. Jackson swatted 10 extra-base hits – six doubles, a pair of triples, and two dingers – in just under 100 trips to the plate with the franchise’s Arizona Summer League team. His overall production, by the way, topped the league average mark by 28% as he hit a solid .280/.344/.476. Seattle may have gotten a little too greedy – though, that’s certainly up for debate – as they pushed the teenage prospect up to the Midwest League to start last season. The 6-foot-2, 215-pound Jackson would bat an utterly disappointing .157/.240/.213 with just six extra-base hits, all doubles, through his first 28 contests with Clinton before an undisclosed left shoulder injury forced him to shut it down for more than a month.

Upon his return Seattle opted to push him down to the Northwest League where he would bat .239/.365/.466 with 11 doubles, one triple, and eight homeruns in 48 games – though he was forced to miss another month with a hand injury. Overall, Jackson would bat an aggregate .207/.318/.365 in just over 300 trips to the plate.

Projection: It appears – a key word here – that Jackson’s first full season was a quite loss. But let’s break it down for a bit. First, I’m willing to ignore the 28-game stint with Clinton last season for a pair of reasons:

  1. He was 19 and tallied just 94 plate appearances in professional ball prior to the start of the year. The actual surprise would have been if he didn’t struggle at the outset of the year.
  2. Who knows how long the left shoulder was bothering him before he actually got shutdown. Did it pop up? Was it a lingering issue? I don’t know, but in this case it’s certainly reasonable enough to look past the poor production line.

Let’s breakdown his work with the AquaSox in the Northwest League: after returning from the DL in mid-June Jackson batted a more-than-respectable.259/.355/.444 over the course of his next 23 games. And then the second injury hit, which forced him out for nearly a full month. After he got back from that ailment he would bat .220/.375/.488 – a reasonable facsimile to his pre-injury line. So in a level of competition still a year or two his senior, Jackson would top the league average by 40% on the back of solid OBP skills and that prodigious power.

Not for some bad news: the borderline red flag strikeout rate he displayed during his debut (25.5%) blossomed into a more troublesome mark last season (30.2%). Jackson’s never going to his for a high – hell, even a higher-ish – batting average, but he could be a very solid Three True Outcomes hitter in the coming years.

Ceiling: 3.0- to 3.5-win player

Risk: Moderate to High

MLB ETA: 2018


3. Luiz Gohara, LHP                                                    
Born: 07/31/96 Age: 19 Bats: L Top CALs: Richard Alvarez, Juan Perez,

Jose Martinez, Kelvin De La Cruz, Raynu Guichardo

Height: 6-3 Weight: 210 Throws: L

YEAR Age Level IP W L ERA FIP K/9 BB/9 K% BB% HR/9 LOB%
2013 16 R 21.7 1 2 4.15 3.06 11.22 3.74 27.6% 9.2% 0.42 60.1%
2014 17 R 12.7 1 1 2.13 1.98 11.37 1.42 31.4% 3.9% 0.00 69.2%
2014 17 A- 37.3 0 6 8.20 6.26 8.92 5.79 19.8% 12.8% 1.45 48.1%
2015 18 A- 53.7 3 7 6.20 4.27 10.40 5.37 24.0% 12.4% 0.67 59.6%
2015 18 A 9.7 0 1 1.86 4.22 4.66 5.59 12.2% 14.6% 0.00 87.5%

Background: Signed as a 16-year-old out of Brazil in 2013 for a shade under $900,000, Gohara’s brief minor league career can be summed up with three different statements: poor luck, problematic control, and a promising ability to miss bats. The 6-foot-3, 210-pounder was aggressively pushed into the Appalachian League immediately after signing with the organization, throwing 21.2 innings while fanning 27 and walking nine. He would make a pair of dominant starts in the Arizona Summer League before spending the rest of his abbreviated sophomore campaign with the Everett AquaSox two years ago, posting a 53-to-26 strikeout-to-walk ratio in 49.2 innings of work. Seattle bounced him between the Midwest League and short-season ball in 2015 where he would total a career high 63.1 innings with 67 punch outs and 38 walks.

Projection: Something interesting to note which could be something or just as easily be nothing: opponents have been exceedingly lucky while squaring off against the big lefty as they’ve posted BABIPs ranging from .333 all the way up to .404 in each of his five (brief) minor league stops. The control remains a work in progress, but teenage southpaws that can fan nearly 10 punch outs per nine innings in the Northwest League are certainly worth watching. There could be some #2/#3-type upside here, but he has a long way to go to get there.

Ceiling: 3.0- to 3.5-win player

Risk: High

MLB ETA: 2018/2019


4. D.J. Peterson, 1B/3B                                                  
Born: 12/31/91 Age: 24 Bats: R Top CALs: Luke Hughes, Danny Valencia,

Brandon Jones, Kyle Reynolds, Nick Evans

Height: 6-1 Weight: 210 Throws: R

2013 21 A- 123 6 0 6 0.312 0.382 0.532 0.220 10.6% 14.6% 162
2013 21 A 107 5 1 7 0.293 0.346 0.576 0.283 6.5% 22.4% 155
2014 22 A+ 299 23 1 18 0.326 0.381 0.615 0.289 7.7% 21.7% 154
2014 22 AA 248 8 0 13 0.261 0.335 0.473 0.212 8.9% 20.6% 126
2015 23 AA 393 19 2 7 0.223 0.290 0.346 0.123 7.9% 22.9% 80
2015 23 AAA 14 1 0 0 0.214 0.214 0.286 0.071 0.0% 21.4% 24

Background: Overshadowed by some guy named Kris Bryant in the 2013 draft, though the former New Mexico slugger’s offensive output was definitely influenced by the school’s home ballpark, Peterson, for the first time since his pre-college days, failed to do the one thing he’s always done last season: hit. After making quick work of the Northwest and Midwest Leagues during his pro debut three years ago, the 6-foot-1, 210-pound corner infielder slugged .297/.360/.552 during his follow-up campaign with High Desert – another offense-inducing environment – and Jackson in 2014. Last year, however, Peterson looked lost in his return trip to the Southern League, hitting a disappointing .223/.290/.346 in 93 games. Seattle would, nonetheless, bump him up to Tacoma, but an Achilles issue shut him down after only 14 plate appearances. For his career, Peterson’s sporting a solid .273/.336/.480 triple-slash line.

Projection: Here’s what I wrote prior to the draft three years ago:

“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.”

And for the first two seasons Peterson looked every bit the part of power-hitting corner infielder. But, for whatever reason, his pop dried up last year as he posted the lowest ISO of his professional – and collegiate – career. Otherwise, all the other numbers fall in line with his career norms: solid eye, BABIP, punch out rate, etc… His power did seem to return in the Arizona Fall League, though he managed to finish that season with another disappointing line: .203/.321/.388. Something inexplicable is up with Peterson, and, unfortunately, it looks like it could warp his career path – if it already hasn’t.

Ceiling: 2.0-win player

Risk: Moderate to High

MLB ETA: 2016/2017


5. Tyler O’Neill, LF/RF                                                
Born: 06/22/95 Age: 21 Bats: R Top CALs: Cristian Santana, Trayce Thompson,

Cody Johnson, Domingo Santana, Michael Burgess

Height: 5-11 Weight: 210 Throws: R

2013 18 R 116 5 3 1 0.310 0.405 0.450 0.140 10.3% 23.3% 143
2014 19 A 245 9 0 13 0.247 0.322 0.466 0.219 8.2% 32.2% 124
2015 20 A+ 449 21 2 32 0.260 0.316 0.558 0.297 6.5% 30.5% 128

Background: A short, stocky, built-like-a-brick-shit-house outfielder out of a Canadian prep school three years ago, O’Neill’s blossoming power potential falls short to only one other player in the system: 2014 first round pick Alex Jackson. O’Neill, like his budding bash brother, had a phenomenal – albeit short – professional debut in the Arizona Summer League as he slugged .310/.405/.450 with five doubles, three triples, and one homerun while topping the league average mark by 43%. He, like Jackson, suffered through an injury-shortened sophomore campaign in the Midwest League, hitting .247/.322/.466. Last season Seattle continued to aggressively challenge the 5-foot-11, 210-pound corner outfielder by assigning him to the California League. And he looked at ease for the most part as he slugged .260/.316/.558 with 21 doubles, a pair of three-baggers, and 32 long balls, easily one of the best marks in all the minors.

Projection: So here’s what I wrote in last year’s book:

“And now the bad news: he punched out in nearly one-third of his plate appearances [in 2014]. Good power, decent eye, O’Neill wasn’t really ready for full season ball. He might be this time around though. A poor man’s Three True Outcomes hitter. Maybe”

Well, if 2015 proved anything it was the fact that, yes, O’Neill is on the path of a poor man’s Three True Outcomes hitter. Incredible, game altering power? Check. Massive swing-and-miss tendencies? Double-check. Below-average walk rates, the lone skill keeping him from a genuine, real life TTO hitter? Unfortunately, check. And not to complicate matters – or throw salt into the wound – but CAL links him to a bunch of toolsy former top prospects that never panned out due to their high punch out rates.

Ceiling: 2.0-win player

Risk: High

MLB ETA: 2018


6. Boog Powell, OF                 
Born: 01/14/93 Age: 23 Bats: L Top CALs: L.J. Hoes, Mallex Smith,

Adam Eaton, Brett Gardner, Dalton Pompey

Height: 5-10 Weight: 185 Throws: L

2013 20 A- 245 7 3 0 0.283 0.364 0.344 0.061 10.6% 13.9% 118
2014 21 A 311 7 4 3 0.335 0.452 0.429 0.094 17.0% 15.8% 160
2015 22 AA 274 6 6 1 0.328 0.408 0.416 0.088 10.6% 13.9% 139
2015 22 AAA 246 10 3 2 0.257 0.360 0.364 0.107 13.0% 16.7% 114

Background: No relation to former MVP slugger Boog Powell, the Rays acquired Powell 2.0 from the A’s as part of the Ben Zobrist package in January 2015 and flipped him to Seattle this offseason. The outfielder, unsurprisingly, is the quintessential Oakland-type prospect: an overlooked, late-round draft pick that has had a tremendous amount of success despite some glaring deficiencies, namely power. But despite the obvious lack of pop, Powell continued his climb up through the minor leagues. After getting popped for amphetamines last season, the former 20th round pick out of Orange Coast College opened the year with Montgomery, where he batted .328/.408/.416. Sixty-one games later he got pushed up to Durham, where he would post the second lowest wRC+ mark of his career, a still respectable 114.

Projection: Again, there’s a clear lack of pop in Powell’s bat – his career ISO is a lowly .079 – and he doesn’t run a whole lot either. But what he does do is invaluable: get on base. Through his first 294 games, Powell’s sporting a .401 OBP with a walk rate approaching 13%. He has the ability to man each of the outfield positions, which only adds value, but I’m not certain he can consistently be a league average regular. He’s a less-speedy version of Billy Burns.

Ceiling: 1.5-win player

Risk: Moderate

MLB ETA: 2016


7. Zack Littell, RHP                                                         
Born: 10/05/95 Age: 20 Bats: R Top CALs: Lucas Lanphere, Casey Shake,

Chadwick Kaalekahi, Ronald Herrera, Sam Gibbons

Height: 6-3 Weight: 190 Throws: R

YEAR Age Level IP W L ERA FIP K/9 BB/9 K% BB% HR/9 LOB%
2013 17 R 33.3 0 6 5.94 4.37 7.56 3.51 18.4% 8.6% 0.54 51.8%
2014 18 R 69.7 5 5 4.52 3.15 8.27 1.55 21.6% 4.0% 0.39 62.8%
2015 19 A 112.7 3 6 3.91 3.27 6.71 2.40 17.4% 6.2% 0.32 61.6%

Background: A late-round pick three years ago, Seattle unearthed the promising former prep pitcher in the 11th round, the 327th overall player taken that year. Since then, Littell’s been stuffing the stat sheet with impressive strikeout-to-walk ratios: he posted a 28-to-13 mark in the Arizona Summer League; he followed that up with a 64-to-12 showing with Pulaski, and finished with an 84-to-30 strikeout-to-walk ratio in 112.1 innings with Clinton in the Midwest League last season. For his career, Littell is averaging 7.3 strikeouts and just 2.3 walks every nine innings to go along with an unlucky 4.42 ERA.

Projection: One of those sneaky good prospects nobody is talking about. Littell hasn’t been mentioned a whole lot about likely because of his poor ERA. But he’s consistently outperformed them, in particular his 3.15 FIP in 2014 and last year’s 3.27 mark. He has some promising swing-and-miss ability, a strong feel for the strike zone, and generates a whole lot of contact on the ground. It’s a recipe for success. Hopefully he can avoid the injury nexus and reach his potential as a #4-type arm.

Ceiling: 1.5-win player

Risk: Moderate

MLB ETA: 2019



8. Tony Zych, RHP                                                      
Born: 08/07/90 Age: 25 Bats: R Top CALs: J.R. Graham, Scott Diamond,

Andrew Heaney, Lucas Luetge, Merrill Kelly

Height: 6-3 Weight: 190 Throws: R

YEAR Age Level IP W L ERA FIP K/9 BB/9 K% BB% HR/9 LOB%
2013 22 AA 56.0 5 5 3.05 3.13 6.43 3.38 16.5% 8.6% 0.32 61.3%
2014 23 AA 58.3 4 5 5.09 3.74 5.40 2.78 13.8% 7.1% 0.46 65.4%
2015 24 AA 16.7 0 0 2.16 1.68 9.72 0.00 29.0% 0.0% 0.00 71.4%
2015 24 AAA 31.7 1 2 3.41 3.13 10.52 2.56 27.4% 6.7% 0.57 78.2%

Background: A fourth round pick under the Cubs’ previous regime in 2011, Seattle just straight up purchased the hard-throwing right-hander from Chicago in early April last season – an incredibly savvy move as the former University of Louisville product easily had his finest season to date. After battling through some lackadaisical strike out rates the previous two seasons, the 6-foot-3, 190-pound hurler exploded in 14 appearances with Jackson – he tossed 16.2 innings with a perfect (literally) 18-to-0 strikeout-to-walk ratio and allowed just four runs, three of which came in one appearance – and tallied another 37-to-9 strikeout-to-walk ratio in 31.2 innings with the PCL Rainiers as he spent the majority of the year yo-yoing between Class AA and Class AAA. Seattle would call him up in early September where he would post another impeccable 24-to-3 strikeout-to-walk in 18.1 innings of work.

Projection: It’s pretty easy to see how Zich can rack up strikeouts with the best of them: his fastball averaged a smidge over 96 mph during his admittedly brief tenure in the big leagues. He complemented it with a low- to mid-80s slider and a hard, high-80s changeup. And even though the Mariners’ bullpen is loaded with a bunch of promising – sometimes dominant – arms, Zych should easily see a fair amount of action, potentially even working his way into some high leverage situations as he continues to earn the trust of new manager Scott Servais. One more thought: CAL seems to be a pretty big fan as well.

Ceiling: 1.0- to 1.5-win player

Risk: Low to Moderate

MLB ETA: Debuted in 2015


9. Andrew Moore, RHP                                                 
Born: 06/02/94 Age: 22 Bats: R Top CALs: Daniel Gossett, Matthew Bowman,

Justin Masterson, Zachary Neal, Kevin Brady

Height: 6-0 Weight: 185 Throws: R

YEAR Age Level IP W L ERA FIP K/9 BB/9 K% BB% HR/9 LOB%
2015 21 A- 39.0 1 1 2.08 2.29 9.92 0.46 28.5% 1.3% 0.46 75.3%

Background: The club’s second pick in the draft last June – as well as their second pick in the second round – Moore was a three-year mainstay in Oregon State’s rotation, leaving the school with 210 strikeouts, just 66 walks, and a 2.00 ERA in 302 innings of work. Seattle sent the 6-foot, 185-pound right-hander to the Northwest League for his debut. And in 39.0 innings with Everett, Moore would post an impressive 43-to-2 strikeout-to-walk ratio with a 2.08 ERA.

Projection: Despite a relatively large sample of near-dominance with Oregon State, Moore isn’t your prototypical flame-throwing right-hander. He does a fantastic job limiting walks and generally inducing a lot of weak action off the bat. With that being said, he profiles more as a fringy big league starter.

Ceiling: 1.0- to 1.5-win player

Risk: Low to Moderate

MLB ETA: 2018


10. Joe Wieland, RHP                                                   
Born: 01/21/90 Age: 26 Bats: R Top CALs: Tony Pena, Chris Britton,

Chris Resop, Brad Thompson, Rafael Perez

Height: 6-2 Weight: 205 Throws: R

YEAR Age Level IP W L ERA FIP K/9 BB/9 K% BB% HR/9 LOB%
2014 24 R 6.0 0 1 3.00 1.20 15.00 1.50 45.5% 4.6% 0.00 50.0%
2014 24 AA 9.0 0 1 2.00 3.56 6.00 1.00 17.7% 2.9% 1.00 79.0%
2014 24 AAA 23.7 2 1 3.42 3.07 7.61 1.52 20.8% 4.2% 0.38 69.1%
2015 25 AAA 113.7 10 5 4.59 3.52 7.28 1.98 18.9% 5.1% 0.55 64.6%

Background: A cog in the massive San Diego overhaul during the 2014-2015 offseason that brought former MVP Matt Kemp to Petco Park. Thanks to a previous round of Tommy John surgery, Wieland topped the 100-inning mark for the first since 2011. Pitching almost exclusively for Oklahoma City in the Pacific Coast League last season, the former fourth round pick posted peripherals eerily similar to that of his pre-TJ days: 7.28 K/9 and just 1.98 BB/9. He suffered through some bad luck, namely an unsightly .355 BABIP, but his 3.52 FIP is clearly more indicative of his true talent than the 4.59 ERA.

Projection: One these guys that often are overlooked because he lacks a traditional out pitch. No blistering fastball (it’s hovered around the 90-mph mark during his cups o’ coffee at the big league level), no knee-buckling deuce, or Johan Santana-like change up. But Wieland knows how to pitch. And he’s been incredibly successful with this approach since entering pro baseball as a fourth round prep arm. Any pitcher that’s sporting a career MiLB strikeout-to-walk ratio of more than 4.5-to-1 has MLB value. You just get the feeling he’s going to be one of these late-blooming quasi-finesse guys that finds a permanent home somewhere.

Ceiling: 1.0- to 1.5-win player

Risk: Low to Moderate

MLB ETA: Debuted in 2012




Note: All statistics courtesy of


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: