Let me start out by saying that, while the farm system has been fun this year, it still lacks an abundance of talent. Yes, there has been a massive uptick in winning percentages all across the board, but more wins does not necessarily equate to more talent. The farm system is still one of the worst in baseball, although the additions of Kyle Lewis, Joe Rizzo, and Dan Vogelbach have it looking much stronger than it did a few months ago.
Barring a fire sale, significantly improving the farm overnight just doesn't really happen. All you can hope for is that the talent that currently exists in the system takes a big step forward and gives their stock a little boost. For the Mariners, here are some of those guys:
Zack Littell – RHP – High-A Bakersfield Blaze
Littell was fairly forgettable in his first three years in the system. While the peripherals were good, the results were often poor, leaving him without much fanfare following the 2015 season. This year, however, Littell has experienced a surge in both his command and stuff. The 20-year-old posted the highest k-rate of his career in his 16 starts with Clinton this season, striking out batters at a rate of 8.75 K/9. The always dazzling walk-rate improved as well, dropping from 2.40 BB/9 in 2015 to 1.94 in 2016.
The performance earned him a promotion to High-A Bakersfield, where he's been nearly as dominant so far. Through four starts with the Blaze, he's managed a 2.73 FIP, 1.13 ERA, and a 6.33 K/BB ratio.
Littell's go-to pitch is a fastball with life that he'll run up near the mid-90s and spot all over the zone with ease. He'll sit in the lower-90s with it, but the movement and command of the pitch helps him maintain effectiveness. His curveball is a big looper that he's comfortable throwing for strikes and using as a primary offspeed pitch. The development of his changeup will be a big key in how effective Littell can be as a starter as he moves through the system.
Littell's ceiling still isn't crazy high, but his vault up the prospect rankings this year has been impressive.
D.J. Peterson – 1B – Triple-A Tacoma Rainiers
Peterson's 2015 season was a tailspin of dramatic proportions that sent him from Top-100 prospect lists to a walk on a tightrope amongst a prospect graveyard. His mechanics were broken, his wRC+ was 80, and he entered 2016 so far outside the conversation for starting first baseman that I'm pretty sure most people forgot he existed.
Fast forward a few months and D.J. Peterson is the best-hitting prospect in the system not named Tyler O'Neill. Big changes to his mechanics have allowed him to use the whole field and cover the strike zone better. I spoke more about his mechanical changes shortly before he was promoted to Tacoma, but the gist of it is this: it's amazing how much easier hitting is when your whole front half isn't flying open on every pitch.
So far in 2016, Peterson has posted a 131 wRC+ in 312 PA with Jackson and a 128 wRC+ in 93 PA with Tacoma. His most impressive stretch came in the month of June when he hit .323/.391/.604 with a 182 wRC+ over a 25-game stretch. Suddenly, he is back in the conversation regarding the future of first base. The acquisition of Dan Vogelbach has made details a little murky, but Peterson is very much in the conversation.
Tyler Herb – RHP – Double-A Jackson Generals
Like Littell, Herb was a very off-the-radar pitching prospect who suddenly transformed into a dominant arm in 2016. In 15 starts with the Blaze this year, Herb posted a 25.6% strikeout percentage while cutting his walks down quite a bit from 2015. His fastball-slider combination dominated the Cal League, leading to a promotion to Jackson a few weeks ago. He's struggled to command his fastball during his time there, posting an ugly 6.00 BB/9 mark through his first 21.0 IP as a result.
The fastball–a low-90s two-seamer with impressive downward sink–is difficult to square up when he's locating well and his sharp-moving slider flashes plus potential. All of that combined with his large 6'4 frame makes Herb an intimidating presence on the mound. If he manages to put it all together, he has the potential to be an effective pitcher for the Mariners in some capacity at some point in the next couple years. This all comes after a very subpar 2015 season that had Herb looking like nothing more than an organizational guy. Baseball is a good game sometimes.
The Sudden Health of Jake Zokan – RHP – High-A Bakersfield Blaze
Typically you take any 25-year-old's performance in the Cal League with a massive grain of salt, but Jake Zokan's case is a little different. Zokan has struggled with injuries since pretty much the moment he was drafted in the ninth round out of College of Charleston back in 2013. He flashed dominance on the mound in between DL trips, but they always came in such small sample sizes that it was difficult to put much stock in the guy at all.
Since coming off of the DL on May 21st and switching over to a full-time reliever, Zokan has been brilliant. In 31.0 IP, he's posted a 0.29 ERA and a 1.60 FIP with an 18.50 K/BB ratio. The switch to the bullpen should help him stay healthy in the future, giving him a very real chance to get himself back on the radar again.
Edwin Diaz – RHP – Seattle Mariners
Anything I say about Diaz will pale in comparison to everything Kate said yesterday. When Diaz was converted to a reliever early in the year, he was expected to be a solid bullpen arm for the Mariners fairly soon. What we didn't expect was that he'd come up and set the whole damn world on fire and watch it burn with unshakeable confidence. Diaz could struggle eventually, but at the moment he's an unstoppable force plowing through immovable objects.
44 strikeouts in 21.2 IP. My goodness.
Guillermo Heredia – OF – Triple-A Tacoma Rainiers
There were a lot of unknowns surrounding Heredia when the Mariners inked him to a contract around the start of Spring Training. Scouts seemed to agree he was close to being MLB ready, with the only major area of concern being his bat. Heredia hadn't played organized baseball in close to two years; his last full season came in 2013, when he hit .255/.376/.349 with Matanzas in the Cuban National Series.
Because of all this, it was particularly surprising when he went down to Jackson and proceeded to rake, slashing .293/.405/.376 with a 13.8% walk-rate and and a 12.3% k-rate in 260 PA. His performance earned him a promotion to Tacoma, where he's perfectly mimicked his 132 wRC+ with a little extra pop (.350/.395/.476).
At the beginning of the year, Heredia appeared to be a fourth outfielder at best. Now, he's starting to shape into a player you'd be perfectly content with trotting out on a daily basis, perhaps in the very near future.
Dylan Unsworth – RHP – Double-A Jackson Generals
I hesitated to include Unsworth here because injuries have rendered his big start to 2016 a small sample, but tossing out extra recognition never hurt anyone. Unsworth has been in the system so long that it's easy to forget he's still just 23-years-old, but a big performance in WBC qualifiers had him picking up steam heading into the season. Pitching for South Africa during a qualifying game in early February, Unsworth tossed eight innings of two-hit baseball after flirting with a no-hitter for awhile in a 7-1 victory over New Zealand.
Unsworth carried that momentum with him to Jackson, where he posted a 1.16 ERA and 2.95 FIP in 46.2 IP before a leg injury sidelined him. He still doesn't possess a plus pitch or anything that suggests he'll be anything more than a back of the rotation starter at best, but his improved command and ability to pound the strike zone has him looking like more of a lock to eventually reach the big leagues.
These aren't all the players who've boosted their stock, obviously. I wrestled with the idea of including guys like Tyler O'Neill, Jordan Cowan, and Dan Altavilla, but decided against it for various reasons. Every minor league system has an endless array of players and I'm sure there are a few whose surprising performances have stuck out to others far more than they've stuck out to me. Regardless, the farm system is fun again, and I feel like there are quite a few more players to lend your attention to this season than there were last year.