Do Justin Dunn, Justus Sheffield fit into Mariners’ pitching plans?

Mar 1, 2022, 10:56 AM
Mariners Justin Dunn...
Mariners pitcher Justin Dunn reacts after Rafael Devers hit a home run for Boston on April 22, 2021. (Photo by Maddie Meyer/Getty Images)
(Photo by Maddie Meyer/Getty Images)

While one of the most anticipated seasons in Mariners history is on hold until the MLB lockout ends, we’re not letting that get in our way of breaking down why 2022 should be a big year for baseball in Seattle. Keep your eye on for a series of articles looking at important topics for the Mariners. In the coming days, we will be focusing on the starting rotation.

In this post,’s Brent Stecker looks at two young pitchers who have struggled to establish themselves with the Mariners. Find links to earlier posts on questions about the rotation at the bottom of the article.

The Mariners have two former top prospects whose 2021 seasons were marred by injury, and they now go into 2022 with big question marks about where they fit with the team.

Bob Stelton: ‘No excuses’ for Mariners with playoff expectations in ’22

Actually, I should rephrase that, because the Mariners have two players who fit that description on both the offensive and pitching sides.

On offense, those players are 2020 American League Rookie of the Year Kyle Lewis and 2020 AL Gold Glove first baseman Evan White. The pitchers, who we’re going to focus on here, are left-hander Justus Sheffield, who took a disappointing step back last year, and righty Justin Dunn, who has shown that he has great stuff but has not shown that he can harness it against big league hitters.

Sheffield, 25, was the bigger concern last year. While he had a strong 3.58 ERA in 10 starts in 2020, he was hit around all of 2021 and finished with a 6.83 ERA, 1.842 WHIP, and a low 1.47 strikeouts to walk ratio. He bounced between the Mariners’ starting rotation, bullpen, Triple-A Tacoma and the injured list due to a forearm strain, and for much of the final month was used as the guy Seattle turned to in relief when the M’s found themselves down by several runs.

The big issue? Sheffield struggled finding a true out pitch, which was all the more disheartening considering how he had seemed to have a breakthrough the year before with a two-seam fastball.

There’s probably more hope that Dunn, 26, could still be able to put it all together than with Sheffield. In fact, some of his numbers were encouraging last season – 3.75 ERA, 8.8 strikeouts per nine innings. The stuff was there but command remained an issue, which is still a bit surprising since that wasn’t the case in his rise through the minors. In five minor league seasons, Dunn averaged 3.4 walks per nine innings and a 2.83 strikeouts to walk ratio. In his 11 starts for Seattle in 2021, those numbers were 5.2 and 1.69.

Then there’s the injury. Shoulder inflammation took Dunn out of action in mid-June, and he managed just four pitches in a September rehab start with Tacoma before needing to leave due to discomfort.

So how do Sheffield and Dunn fit in Seattle’s pitching staff for 2022? As things stand now, the Mariners have four pitchers set for the five-man rotation, so a strong spring training could conceivably land either in the rotation. But that’s not really all that likely as the M’s aren’t believed to be done adding to the rotation. Plus, it would honestly be ill-advised to go into such an important season with a question mark in that fifth spot.

That being said, health permitting, I would expect Dunn to get more than a few chances to start games this season for Seattle. In this day and age, starting pitching depth needs to go far beyond the five-man rotation, and Dunn is a strong candidate to be sixth on the depth chart.

Sheffield, meanwhile, appears to have a tougher path back to starting games. Considering the Mariners used him out of the bullpen down the stretch last year, it seems logical that he would begin 2022 fighting for a relief role as he looks to find a pitch repertoire that can get MLB hitters out.

Not all former top prospects pan out. In fact, most don’t. But while the book isn’t closed on Dunn and Sheffield, 2022 figures to be both a very important year for them and one in which it may be hard for them to find opportunities.

More from our series on the Mariners’ rotation

Shannon Drayer: How will 4 big M’s prospects figure into rotation?
Brandon Gustafson: What to look for from Marco Gonzales, Chris Flexen

Date Starting Pitcher
Wednesday, May 18 @ 4:07 pm Mariners' Marco Gonzales vs. Blue Jays' Kevin Gausman

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