Organization Ranking: 21
I've ranked every farm system, as well as the top 100 MLB prospects for 2015. Below, I've ranked at least the top 10 M's prospects, plus an overview of the system and any other names of note beyond the top 10. I also discuss any prospects who might help the big league club in 2015, one or two prospects whose stock has taken a big hit in the past year, and a sleeper prospect who I think can jump into the main top-100 list for 2016.
Non-Insider subscribers: Check out the free Tampa Bay Rays top-10 prospects report to see what these entail.
Top 10 prospects
1. Alex Jackson, RF
2. D.J. Peterson, 1B/3B
3. Austin Wilson, RF
4. Ketel Marte, IF
5. Gabriel Guerrero, RF
6. Luiz Gohara, LHP
7. Edwin Diaz, RHP
8. Tyler Marlette, C
9. Patrick Kivlehan, 1B
10. Gareth Morgan, OF
Overview
The Mariners graduated two top pitching prospects, Taijuan Walker and James Paxton, off their list from last year, but most of the best prospects who remained in the system had great or at least very good seasons, with few expections. They also added two high-upside prep bats in their 2014 draft class, led by Jackson.
Wilson's been a favorite of mine for years, and he was playing well in low-A, a league for which he was too old, but he played just 10 games after June 24 due to injuries. He needs to have a full, healthy season this year, get himself to Double-A and perhaps the Arizona Fall League, because for all of his ability he's about to turn 23 and hasn't reached high-A yet. Marte came out of nowhere this year to hit .304 at two levels with 29 steals and a low strikeout rate. He's excellent defensively at second base, solid at short, and could probably handle second base, which could make him a good utility player. His swings on both sides of the plate have some loop length, with the finish to produce some power once his lean 20-year-old body fills out a bit. He doesn't walk at all, so if his batting averages ever slip, he's going to have a hard time being an everyday player for anyone.
Guerrero has the family trait of trying to hit everything thrown at him because he can make a lot of contact on pitches out of the zone, but he does have above-average power and a good arm, with enough bat speed to make you think he could be a regular if he can be more selective. He'll play in Double-A this year at age 21, young for the level, but also out of the hitter's paradise of High Desert. Diaz has come a long way in two and a half years in the Mariners' system, sitting 92-96 mph with a much improved breaking ball; his body has filled out substantially and he has a real delivery now, something he can use and repeat to maybe get to average command. Marlette is an offensive catcher with above-average pop and a plus arm (nailing 35 percent of runners last year); his issues have been receiving, framing, and blocking, although he has improved, especially at blocking balls in the dirt. Kivlehan is famous as a former football player at Rutgers who played just one year of baseball. He has above-average bat speed and maybe 15-20 homer power, but is a below-average runner and I think he'll have to play first in the majors. Morgan had an atrocious pro debut, striking out in 41 percent of his plate appearances. The Canadian 18-year-old was the Mariners' second-round pick and has a pretty swing with pull power; he's just raw, more so than I think most scouts realized last spring.
Ryan Yarbrough (11), their fourth-round pick in 2014 out of Old Dominion, is 92-94 from a low ¾ slot and a good changeup; it's not a great delivery for a starter but he pounds the strike zone and could end up a quality No. 5 starter if the breaking ball improves. Victor Sanchez (13) doesn't walk many guys, but his stuff is meh and the body has no projection to it, so he's going to have to prove himself at higher levels to have asset value. Tyler O'Neill (14) was in the midst of a strong full-season debut, with 13 homers in 57 games at age 19, when he broke his hand punching a dugout wall. Third-rounder Austin Cousino (15) might be a good fourth outfielder, as he can run and play centerfield, with solid bat-to-ball skills that just won't produce much power. Catcher Steve Baron (16), who appeared to be a bust at this time last winter, actually showed some signs of life at the plate in an odd season where he only played part-time, in part so Marlette could get regular duty; Baron has a career 46 percent CS in 385 attempts, so he'd only have to hit a little bit to make a career for himself as a backup.
And since you're probably wondering, Danny Hultzen was throwing to live hitters in the fall and feeling good a year off shoulder surgery, with some minor mechanical changes to get him more online to the plate now.
2015 impact
Carson Smith (12) should be a key middle reliever for the M's this year; he comes from a low slot with mid-90s velocity and a sharp slider that should make him death to right-handed hitters.
The fallen
Tyler Pike, their third-round pick in 2012, walked 80 men in 110 innings across two levels and pitched with a below-average fastball for a good chunk of the season.
Sleeper
Gohara gets comparisons to a young CC Sabathia for his strong, thick build, and he's had outings where he's come out 94-96 with a plus curveball. He also pitched at 17 most of the summer, and made three starts when he couldn't retire more than three batters. He still has a lot of maturing to do, both as a pitcher and as a person, but in his defense, he's younger than every high school pitcher drafted in the first or sandwich round in 2014 and has already spent two summers in pro ball.