Mariners 2015 Prospects of the Year

It’s usually not difficult to identify the players of the year in minor leagues of a big-league organization. Determining the prospects of the year isn’t necessarily as elementary. In fact, it never is in my experience. The difference? Player of the year typically is all about performance. Prospect of the year is significantly more intricate and sophisticated, and requires a lot deeper and widespread investigating.

The Seattle Mariners have what many call a weak farm system. I don’t entirely disagree, since a large portion of the club’s talent spent 2015 playing below Double-A Jackson and many of its best upper-level prospects struggled. Several intriguing talent stand out, however, including the prospects of the year, who displayed a combination of development and performance.

Pitching Prospect Of the Year: Edwin Diaz, RHP
Diaz, 21, still strikes most scouts as a likely reliever due to a sleight stature and relatively shallow repertoire. The right-hander does tend to fall in love with his slider at times, but for good reason — it’s plus, inducing swings and misses while serving as an offering he also can throw for called strikes.

Diaz began the season in Advanced-A Bakersfield but after seven strong starts was promoted to Jackson. With the Generals, as he faced a more legitimate level of batting talent, Diaz continued to show solid control of his fastball and slider, a better feel for pitching overall and more willingness to use his changeup, at least at times.

He suffered through some bouts of below-average fastball command; even at 91-96 mph, catching too much of the plate doesn’t work. Still, Diaz’s fastball sinks and tails and he was able to limit the damage, yielding just five long balls in 104 1/3 innings of work.

Reportedly Diaz is up to about 180 pounds to go with his lanky 6-foot-3 frame and easy-effort delivery. He stays on top well, an improvement over a year ago, and he commanded the slider better, too.

Diaz is the easy choice for pitching prospect of the year. He’s the Mariners’ top overall pitching prospect and his growth and production skies over any other in the system.

Others: Dan Altavilla, RHP; Enyel De Los Santos, RHP; Andrew Moore, RHP; Nick Neidert, RHP; Dylan Thompson, RHP; Paul Fry, LHP; Tony Zych, RHP; Emilio Pagano, RHP.

Position Player Prospect of the Year: Tyler O’Neill, RF
Ketel Marte would have been steep competition for O’Neill, but he was promoted this summer and ultimately spent just 11 weeks in the minors. O’Neill had a tremendous campaign, showing his raw power in games and displaying a more mature game plan as the season progressed.

He’s still a little unrefined in some areas, but the former third-round pick also showed above-average instincts on the bases, a more disciplined defensive game and most importantly, at least for his chances to hit, improved pitch recognition.

O’Neill smacked 32 home runs and tallied 65 extra-base hits in 106 games this season for the Blaze in the California League. My inquiries with scouts cover 21 of those 32 long balls and word on all of them suggest exactly zero of them had anything to do with wind or thinner air.

O’Neill has plus bat speed and is starting to learn how to use it for reasons other than the home run. He’s shown leadership skills and as always shows an elite work ethic. Many scouts believe he’s faster now than on draft day 2013, and the club reveals that’s because O’Neill has worked in his speed.

This was a rare year when player of the year and prospect of the year were the same players. Diaz and O’Neill took legitimate, meaningful steps forward.

Others: Drew Jackson, SS; Jabari Blash, RF; Ketel Marte, SS; Patrick Kivlehan, OF; Tim Lopes, 2B.

All-Org Prospect Team
1B D.J. Peterson
2B Tim Lopes
3B Logan Taylor
SS Ketel Marte
C Steve Baron
OF Tyler O’Neill
OF Alex Jackson
OF Jabari Blash
SP Edwin Diaz
SP Dan Altavilla
SP Enyel De Los Santos
RP Paul Fry
RP Tony Zych
RP Emilio Pagan

Jason founded Prospect Insider in 2006 after getting his start at He spent several years covering prep, college and pro sports for various newspapers, including The News Tribune and Seattle PI. Jason spent 4 1/2 years at ESPN and two years at CBS Radio prior to joining HERO Sports in July, 2016.

Find Jason’s Mariners podcast, Baseball Things, at

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