Justus Sheffield Emphasizes Re-Imagining of Mariners’ Roster

The trade of James Paxton and acquisition of Justus Sheffield represents a pivoting point for the Mariners’ organization. The talent on the rise still won’t impress overall, but a system lacking immediate reinforcements just received an MLB-ready top prospect.

The way things are shaping up for the Mariners, Justus Sheffield won’t remain a top prospect for long, but his arrival will be a shot in the arm regardless of what level he pitches at. Dealing James Paxton means the organization will take a step backward next year, yet targeting a major-league-ready prospect like Sheffield as the return emphasizes the club’s intention to compete in the near future rather than rebuild in its most extreme sense.

It would be tough to find a pitcher with greater upside than Sheffield for 2 years of James Paxton — let alone somebody who has also pitched a significant amount in AA and beyond. So not only does Sheffield come with plenty of upsides, but he is ready to show it right now and that was presumably a key part of the deal.

Coming into the 2018 season, FanGraphs’ ranked Justus Sheffield the 39th best prospect in the game. They moved him up to 30th by mid-season at which point MLB Pipeline similarly ranked him 31st, and currently, after an influx of draft talent and some routine moving and shaking, FanGraphs’ thinks of him as baseball’s 54th best prospect.

Regardless of his exact ranking, Sheffield will stand head and shoulders above every prospect in the Mariners’ system.

While some questions about his ability to command the ball exist, presently, Sheffield is thought to offer a repertoire led by two MLB-ready pitches: a mid-90s fastball and a power slider.

The fastball is often a two-seamer. Its movement and velocity have offset the difficulty of creating a downhill plane with his smaller frame (Sheffield is 5’10”) and allowed him to post respectable groundball rates in the minors.

The slider plays against hitters of either handedness and although it doesn’t make Sheffield a strikeout pitcher, it picks up a good amount of whiffs and plays well with his fastball, making him quite difficult to take deep (career 0.59 HR/9).

This above-average-to-plus 2-pitch combo has scouts imagining a successful career in relief as a realistic floor, but Sheffield has maintained his production into the high-minors as a starting pitcher.

He threw virtually all of 2018 between AA and AAA where, despite some rumblings of his stuff and/or command backing up, he posted a combined 2.48 ERA/2.98 FIP in 20 starts (25 games) over 116 IP while striking out 123, walking 50, and giving up just 4 home runs.

That walk rate further underscores concerns about Sheffield’s command, but it is far from unruly and the fact that he was still stingy with home runs (0.31 HR/9) suggests that he was losing the strike zone more so than finding too much of it — arguably, that is less problematic.

Nevertheless, Sheffield is a pitcher with a career 3.08 ERA and 3.37 FIP in the minor leagues. He has excelled every year at every level and he has major-league ready stuff right now. His changeup needs refinement, and its consistency will have a great influence on his long-term outlook, but it is a pitch that already flashes above-average when it’s on.

As he is, Sheffield is a fine back-end starter who will occasionally look brilliant as things intermittently click.

At his best though, he may wield his repertoire masterfully and become a bonafide #2.

In 2019, Justus Sheffield will get a real chance to show the majors what he is made of. Barring early season struggles, he should spend most of his time with the big league club.

While command will dictate where he falls between a #2 and #5 or whether he falls into the bullpen entirely, if recent adjustments and subsequent improvements in command from left-handers Marco Gonzales, James Pazos, and of course, James Paxton is indicative of anything, the Mariners are primed to get plenty out of their new young lefty.