Sodo Mojo’s Top 40 Seattle Mariners Prospects: 10-6

Justus Sheffield is a personal favorite of mine but a lot of people are down on the athletic lefty. This is largely based on his terrible tenure in Tacoma to start the year, but Sheffield righted the ship in AA.

When he has his best stuff, Sheffield’s arsenal includes a fastball 91-94 MPH with good life up in the zone. Sheffield’s best offering is his two-plane slider that can earn 65-grades on any given night. The changeup is a work in progress but flashes average with good arm speed and fade.

Sheffield has a pretty good chance at 3 above-average offerings, but whether or not he can harness those pitches will tell his story. Sheffield shows moments of 55-grade command, but mostly has issues commanding his fastball.

The fastball doesn’t have the velocity to play without command. If Sheffield can gain that skill, he has #3 stuff with athleticism to match. He shows above-average command of his slider and changeup, which may be a good sign for Sheffield’s long-term success with the fastball.

One of the skills Sheffield has shown is his ability to produce ground balls, a skill that shouldn’t be overlooked in the current offensive environment. Sheffield can get swings-and-misses with his slider, generating above-average whiff rates.

2020 will be a big year for Sheffield. He will have the entire season to show what his future with the ballclub can hold, with very little pressure to perform right away. Getting to 160 quality big league innings would be a big step for the 24-year-old in his first full MLB season. With his current command and stuff, a season with a low-4.0 ERA and about a strikeout per inning isn’t out of the question.