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Meet Justus Sheffield, the Mariners’ new top pitching prospect

Félix will always be our King, but maybe Justus can be our Short King

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Boston Red Sox v New York Yankees Photo by Mike Stobe/Getty Images

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Yesterday what we knew was going to happen, but hoped wouldn’t happen, but also recognized the necessity of happening, but also kind of dreaded happening, happened. We spent all these years doting on James Paxton, the last of the Big Three, our remaining homegrown superstar, and they just...traded him away. Later, and once we’ve dried our maple-scented tears, we will have a Requiem on Pax for you, but for now, let’s look at the headliner of the deal the Mariners got in return: LHP Justus Sheffield, our new Short King. (Click for background on Short Kings and the yeoman’s work being done by Jaboukie Young-White in Short King Acceptance.)

[Normally, deep dives on pitching prospects like this are the purview of Jake Mailhot, but Jake cannot be with us today, because he’s about to have a dang ole lil baby girl, or at least that’s what he told us, maybe he just wanted to get in line for the next Star Wars movie. Please offer Jake, who is truly one of the kindest humans I’ve ever had the pleasure to know, your congratulations here, or at his twitter handle @jakemailhot.]

John has written a fair amount on Sheffield in between his proposed trade piece and his blurb on the trade, so if you want the abbreviated scouting report, check in on those pieces. Here we will cover more of Sheffield’s backstory and development up to this point. Jake or John will have the real nitty-gritty mechanical breakdown in a different post.

Justus Kane (!) Sheffield was born in 1996 in Tullahoma, TN, a town of less than 20,000 people 12 miles from Lynchburg, TN, which some of you might recognize as the home of Jack Daniel’s. The Wikipedia page for Tullahoma lists 12 “notable people” from the town, five of whom are baseball players, and two of whom are the Sheffield brothers, Justus and older brother Jordan: a pitcher in the Dodgers system who, at 23, is a year older than Justus, but was sidelined by TJ surgery in 2013 and then chose to attend college and so has just completed High-A and a stint in the Arizona Fall League. (Younger brother Jaxon, 13, is often tabbed by both his older brothers as the best athlete in the family.) As a senior in high school, Justus was already able to pitch in the low 90s with his fastball, and showed promise in his secondary pitches, especially his changeup. Sheffield was named the Gatorade National Baseball Player of the Year in 2014. Cleveland selected him at #31 overall in the draft, and in a brief taste of rookie ball Sheffield was already showing that despite his shorter stature (5’10”), he could run his fastball up to the mid-90s.

Home during the off-season, Sheffield was arrested in January of 2015 for aggravated burglary (it was later reduced to criminal trespass) and underage drinking. The incident stemmed from Sheffield believing that an acquaintance had been messing around with his girlfriend, and with two of his ex-high school baseball teammates, an intoxicated Sheffield broke into the home and accosted the young man in his bedroom with verbal threats. Sheffield pled guilty and received probation, and was ordered to donate $500 to charity (any charity? Not like, community service or something? The Tennessee justice system seems like kind of a trippy place.) The incident was surprising to a number of baseball people who had praised Sheffield’s high-character makeup and his closely-knit family (bringing home worse than a B- from school resulted in the loss of all privileges, and Justus maintained an A average throughout high school), but doesn’t seem to be a recurring pattern of behavior, as Sheffield has kept a clean record for the past four years and for his part, expresses deep regret about the incident:

“I was stupid. I was 18, just immature, really,” Sheffield says now. “I felt like I’ve learned from that mistake. It was probably the hardest thing I’ve had to go through. It was my first off-season and I was 18, and dumb, and immature. I’ve become a better person, a smarter person and definitely more mature. I’ve looked at it as a game of baseball – you can’t always go out there and throw a perfect game or seven shutout innings. We all make mistakes. We’ve got to learn from mistakes. I thank God I was able to get a second chance and prove myself.”

Cleveland dealt Sheffield at the 2016 trade deadline in order to acquire Andrew Miller. Armed with a few more ticks on his fastball, even better bite on his slider, and the still-developing changeup, Sheffield entered the Yankees’ vaunted system ready to improve, and immediately put up even better numbers at High-A than he had in Cleveland’s system.

The Yankees promoted the 20-year-old to Double-A Trenton at the beginning of the 2017 season, and his numbers fell off some, as is typical for many young pitchers in making the jump to the level. He also missed a good chunk of time that year with a strained oblique, so the Yankees sent him to the Arizona Fall League after the season, where he dominated to the tune of 22 strikeouts in 20 innings against some of the game’s best prospects. You might remember Sheffield from this interview from the Fall Stars Game, when Mariners prospect Matt Festa got approximately 0 seconds of screen time during his inning as he sat down the side 1-2-3 during Sheffield’s interview. That’ll be a fun story to tell at Spring Training.

Sheffield started 2018 at Double-A, but after a strong start, despite being one of the level’s youngest pitchers, he was quickly promoted to Triple-A Scranton/Wilkes-Barre. The second-youngest starter with at least 15 starts in the International League, he again saw his strikeouts fall off, but was able to keep his other peripherals in check. One thing Sheffield has done well at every level is keep the ball in the yard, generating generally weak contact and his fair share of ground balls. The Yankees converted him to a reliever towards the end of the season in preparation for a postseason run, and he pitched all of 2.2 innings in the majors.

Some scouts look at the 5’10” Sheffield and see an eventual reliever in the hard-thrower with command issues and two MLB-ready pitches in his fastball/slider combo. Others, like Kiley McDaniel at Fangraphs, see a possible five or six-inning “opener-plus” (that’s my term, it’s a dumb term, don’t yell at Kiley for it, and it’s nicer than the “five and dive” term prevalent in scouting), in the vein of what the Rays are getting out of Tyler Glasnow. Durability issues will always be raised with Short King pitchers, and some have described Sheffield’s delivery as high-effort, although he repeats it well, which makes his command issues puzzling. (John has a theory regarding this and the way Sheffield breaks his hands, which he will expand on next week.)

Aside from the oblique and a sore shoulder that kept him out of one start, the compact, muscular Sheffield has been mostly durable throughout his pro career; he may not be 6’4” but he pitches like it. Sheffield has a big, strong lower body with a big old badonk (no, like, really) and quad muscles that might remind you of fellow hard-thrower and short king-adjacent Dan Altavilla (it should be noted that a short king pitcher is a tall person in any other environment). Durability shouldn’t be the top concern; command and the ability to develop the changeup into an MLB-quality pitch are much more pressing needs.

If Sheffield is a reliever—even a very good one—it will be hard to look at this trade as a success for the Mariners. Paxton was the team’s one big trade chip this off-season, if it’s true that Haniger and Díaz are nigh-untouchable, and several industry types have already opined that the return felt light for the Mariners or the Mariners came up on the shorter end of the trade. The Mariners’ system is devoid of starting pitching; their other two top SP prospects have thrown a combined three innings for the organization (all three belong to Sam Carlson before he went down with TJ surgery). That’s bad! So the Mariners need Sheffield, who is just six months older than 2018 1st-round pick Logan Gilbert, to be a starter. That means they have to solve his command issues and help get that changeup up to MLB-quality, and in order to do both of those things they have to gamble on the fact that they can do something the New York Yankees can’t do, which seems bonkers, especially given the reputation the Yankees have in the industry for developing pitching. [Meanwhile, at Tacoma, I’m told Lance Painter—the pitcher-whisperer responsible for unlocking Pax’s new arm slot—is a maybe to return to the Rainiers, where Sheffield will almost certainly be assigned at least to start the year because of Service Time Shenanigans (STS). So that seems...not ideal.]

The Mariners have had success with bumping up the potential of their lefty starters: the aforementioned new arm slot for Paxton; helping Marco Gonzales develop his cutter and blossom into a solid mid-rotation option; whatever wizardry they worked with Wade LeBlanc to help him post an fWAR on the season that was .1 shy of his combined career fWAR. Control fiend and changeup artist Wade might be a great mentor for young Justus, who is reportedly very teachable, and the Mariners will also have the expertise of mechanics expert Brian DeLunas and new hire Paul Davis, an analytics-minded pitching coach from the Cardinals organization. [John would also like me to mention James Pazos here, who did come over from the Yankees and seem to get his command issues straightened out before a possibly injury-dampened 2018.]

To me, the key question is this: did the Mariners specifically target Sheffield, as they did Marco, because they believe they can unlock something in his profile to push him forward? Or did they cast a wide net hoping to get a certain tier of pitching prospect in return, regardless of organizational fit? Sheffield seems like a fit for the Mariners from a teachability and work ethic standpoint, and will inject a much-needed jolt of youth and upside, as well as a big, fun personality, into a system that’s low on all three. But in a system like the Mariners’, and without executing a full rebuild, snatching up the best MLB-adjacent player available doesn’t by itself guarantee success. What I will be listening for over the next few weeks/months in interviews is an indication that the Mariners have a specific plan in mind for their new short king. Sheffield may be MLB-adjacent, but at just 22, he’s not a finished project as a pitcher (according to Wade the Wise, he needs another decade to even start approaching that mark). The Mariners will have the task of polishing off the rough edges and fitting Sheffield into a major-league rotation, and they will have the time to do it, as the team isn’t expected to compete in 2019, and maybe not in 2020 either. How well they succeed will give fans an idea of how much leeway to afford the beleaguered organization in both their ability to assess talent and develop it.