Justus Sheffield would not have been on this list 6 or 7 months ago but after his encouraging 2020 season, he will not be talked about in any trade discussions. Sheffield only would be brought up in trade talks where the Mariners acquire a star player but even when another team asks if he is available in those negotiations Seattle should say no.
Sheffield has a chance to be a mainstay in this rotation with Gonzales along with the slew of pitching prospects that the Mariners have coming up. Justus started 10 games in 2020 and had a 3.58 ERA and an excellent 3.17 FIP. He had a rough and inconsistent start to the season but had an excellent September when he started 4 games (2 against playoff teams) and only allowed 6 runs in 25 innings.
What was also interesting about Sheffield’s 2020 was that according to Baseball Savant he abandoned his 4 seam fastball in favor of a sinker. He also had consistent control but tended to throw his pitches (Sinker, slider, changeup) in the same spots, so if he can work on his control painting the black more in different spots he could become an ace.
The Mariners have 5 more years of team control on Sheffield and are 2 years away from even hitting arbitration. While we don’t know if it will be a 6 or 5 man rotation in the future, we know that Sheffield will be a part of it.