Minor League Update: 2015's Success Stories

For as bad as the Mariners have been on the field this year, the situation hasn't been much prettier in the minor leagues, where most of the club's top prospects have struggled or regressed in 2015. D.J. Peterson has a .290 OBP and six homers in Double-A. Alex Jackson posted a 38 wRC+ in Low-A Clinton before a shoulder injury gave the Mariners a convenient opportunity to drop him down to short season ball. Austin Wilson is running a .580 OPS in the California League. John Hicks isn't hitting. Gabe Guerrero wasn't either and now he's in the Diamondbacks system. And of course, those poor performances pale in comparison to Victor Sanchez's tragic death last March.

Despite the struggles from Peterson, Jackson, and a few of Seattle's other consensus top ten prospects, 2015 hasn't been all bad. Where some have faltered, others have played well and improved their stock. Today, I want to highlight a few of the players who have taken positive strides over the past few months.

Ketel Marte: Assuming he's still eligible -- he probably will be -- Marte will find a home on the back half of the various top 100 prospect lists posted during the offseason. A switch-hitter, Marte has raked from each side of the plate this year, hitting over .300 against both lefties and righties. He has a decent feel for the strike zone, but he's aggressive when he gets a pitch he can reach, and that trait paired with good bat-to-ball skills means he won't work many deep counts. He'll need to hit for average to have value at the plate and with plus speed and a short stroke geared for line drives, he has the skills to do it.

Defensively, he doesn't have a home yet. A shortstop by trade, Marte made his first start in center field for the Rainiers yesterday, and from an organizational perspective, that's the position that makes the most sense for him going forward. He's still playable at short, but his arm isn't strong for the position and choppy footwork limits the utility of his range. Most organizations would be happy to plug him in at second base, but most teams aren't scheduled to pay Kiribati's GDP to Robinson Cano over the next eight years. Marte has the athleticism to handle center though, and with Austin Jackson likely to depart following the season, there's a chance that he sees the field out there in the next year.

Luiz Gohara: Like last season, Gohara is the youngest pitcher in the Northwest League. Unlike in 2014, he looks like he belongs in the circuit this year, where his control has taken a noticeable step forward and his 95 mile per hour fastball has proven to be too much for most hitters. His changeup and curveball have also improved, and the deuce could be an impact offering for him down the line.

Gohara is only 18 and is still pretty raw for his age, so the Mariners will probably take it relatively slow with him. They like to accelerate their best prospects through the system quickly but it makes sense for them to be more cautious with the Brazilian, and I'd expect him to spend most of next season improving his control and developing some consistency with his offspeed pitches in Clinton. There's a long way to go but he has the highest ceiling of any arm in the minor league system at this point, and his success in Everett is one of the best developments of the year for the player development machine.

Edwin Diaz: Diaz represented the Mariners at the Futures Game this July, where he hit 98 on the gun and looked like the slightest guy on the field. Some are worried that his size -- he's listed at 6-foot-3 and 165 pounds but he looks lighter -- will prevent him from getting the most out of his talent and there's some concern that he's too small to have the stamina to pitch in the rotation over a full season. We can only guess how he'll hold up under the rigors of working as a major league starter, but from a stuff perspective, he should be fine: he sits in the low-to-mid 90's and flashes a plus slider, weapons that will play in a big league rotation even if he doesn't eat too many innings.

After a rough start to his Double-A career, Diaz has pitched well since the calendar flipped to June. He's allowed more than three runs only once in his last nine outings and he's been particularly good lately: over his past three starts, Diaz struck out 20 in 17 innings, allowing three runs while walking two. His command comes and goes and his changeup still lags behind his other offerings, which limits his ceiling to that of a No. 3 or No. 4 starter. He's relatively close to the majors though, and barring any setbacks, could appear in Safeco as soon as next season. If those problems preclude him from working effectively in the rotation, he has the repertoire to be a lights out reliever.

Luis Liberato: A toolsy outfielder from the Dominican Republic, Liberato has impressed in his first spin through the Northwest League. He's a good athlete who can handle center, and he has above average raw power for a player his age. In games, most of his pop is to his pull side in right field but he can hit to all fields and as he gets stronger, he has the swing to put balls over the wall in center too.

Liberato is very raw: he's not fundamentally sound in the field and I've seen him make questionable decisions in the outfield and on the bases. Like Gohara, he's far away, but the tools are impressive and if it all clicks, he'll be one of the most exciting prospects in the system. He's just ten days older than Jackson, and it'll be fun to track the two of them as they climb the minor league ladder together.

Dan Altavilla: An unheralded pick out of a small college in 2014, Altavilla's stuff jumped in the second half of the year in Everett. The Mariners aggressively promoted him to High-A in 2015, and he's held his own in the Cal League, with an ERA under 4 and a 7.7 SO/9 ratio. He sits in the low-90's with his fastball but will touch higher, and his slider has improved significantly during his time in the organization. Like Diaz, he's still working on a changeup, and he'll profile best as a reliever if the pitch never comes around. Either way, it's looking more and more like the M's have turned an under slot pick into a big league pitcher.

Paul Fry: A 17th round selection in 2013, Fry was an all star out of Bakersfield's bullpen this summer, and he's off to a good start in Jackson as well, where he's struck out fifteen hitters and walked one in his first eight innings of work. Fry is a left hander who sits in the low-90's with good run and he pairs the pitch with a two-plane slider that misses plenty of bats. His upside is limited, but he commands both pitches well and he could complete the jump from org guy to big league arm sometime in 2016.