Previewing the 2021 Seattle Mariners

2021 Seattle Mariners

This season the Seattle Mariners enter the third year of their rebuilding plan under GM Jerry DiPoto. Following a 27-33 record last year, they look to build on the winning record they had in the last month of the 2020 season and be ready to challenge for a playoff spot in 2021.

2020 Highlights

The Mariners posted the sixth-best record in baseball from August 21 through the end of the regular season. In that time, they had a record of 19 wins and 14 losses. From August 31 through the end of the regular season, their starting pitchers went 10-5 with a 3.78 ERA, recording 107 strikeouts and 10 quality starts.

The team led the American League in stolen bases with 50, and ranked third in baseball with a .989 fielding percentage. They scored at least four runs in 32 of their 60 games and went 24-8 when scoring at least four runs.

Mitch Haniger Returns

Nearly three years have passed since Mitch Haniger was an All-Star. He was counting on being part of the core to build around. Haniger’s breakout season was 2018. He hit .285 with 26 home runs and 93 RBIs. It seemed to be just the beginning of a great career.

Then the injuries hit. His 2019 season was ended by a ruptured testicle. That led to a torn adductor and herniation of a disc in his lower back which kept him out of action in 2020.

Haniger looked healthy this spring. The hope is he gets at least 130 games in the lineup in right field or at designated hitter. His return comes at a great time not only with his bat but also with his experience. He is regarded as one of the best clubhouse players in baseball.

Offense Needs Improvement

The Mariners offense must be better than last year if they are going to stay in games. They only hit .226 as a team, 24th in the league. They finished 25th in homeruns and 27th in both on base percentage (OBP) and slugging. While some say the abbreviated season affected the young power hitters, others say they are a young team and need more discipline in pitch selecting.

Including Haniger, they have three hitters who could provide the power and hit with runners in scoring position, Kyle Lewis, who will start the season on the IL, Kyle Seager, and Evan White. Lewis, who won the Rookie of the Year award last year, led the team in home runs and batting average last year. Veteran Kyle Seager begins his 11th season in a Mariners uniform. He is consistent and averages 25 home runs and 87 RBI over his career. Evan White made his debut last year. He hit eight home runs but only hit .176. The team is hoping he can be a consistent .285 hitter with 20 plus homeruns a year.


The Mariners are an outstanding fielding team. Their defense will need to be aggressive and ready to support a pitching staff that will struggle with hits. They will need to perform their expertise in fielding with double plays and overall smart fielding plays.

The infield is solid with White at first base and J.P. Crawford at shortstop. Both won a Gold Glove award last season. The outfield looks good with Lewis, who with his arm, strength, and range should be a solid defender.

Two Solid Starters

Marco Gonzales had a tremendous season for the M’s last season, pitching to a 7-2 record and a 3.10 ERA in 11 starts. A lefthander, he is the “ACE” of the staff. It will be up to him to continue the winning streaks — or stop losing streaks should it come to that. We could go into the “sabermetrics” about him but all Mariner fans care about are keeping his innings pitched low and his ERA respectable, his wins, and his strikeouts. It’s good to note that Gonzales does not walk many batters.

A familiar name comes back to Seattle in James Paxton, also left-handed. He signed a one-year-deal Paxton was 41-26 with a 3.42 ERA for the Mariners from 2013-18, striking out 617 and walking 168 in 582 1/3 innings. He is excited to be back with the organization that drafted, developed, and helped him achieve MLB success. Paxton suffered from elbow and back issues. If he’s fully recovered, he and Gonzales give the Mariners solid back-to-back left-handers in their starting rotation.

Other Starters

The Mariners will likely turn to a six-man rotation this season to protect their young arms over the course of 162 games. The rotation will include Justin Dunn, Chris Flexen, Yusei Kikuchi, and Justus Sheffield.

They must improve on both starting pitching and the bullpen ERAs from last year — starting ERA was 5.03; the bullpen, 5.92. Whether they can do it is their biggest question mark for this season.


As for the bullpen, it has to perform better than last year’s, which was absolutely awful in every aspect. Their ERA was 28th in baseball at 5.92. They lost 13 games and gave up 40 homeruns.

The closer will be Rafael Montero, acquired from the Texas Rangers. He brings a fiery fastball in the 95-97 mph range. He also has a changeup that gets plenty of swings and misses against left-handed hitters.

Expect to see Anthony Misiewicz given the ball in crucial moments in 2021. He was one of the team’s most reliable relievers last year. Misiewicz, a left-hander, led the pitching staff with 21 appearances and looked comfortable out of the bullpen in 2020. This bullpen does not have many left-handers so he will play a vital part in the 2021 staff.

Nick Margevicius, who missed the final starter spot, will be included on the big-league roster. The left-hander will be in the bullpen as a long man for at least the first part of the season. Look for him to move back to the starting rotation should any injuries happen to the starters.

As of this writing, final bullpen spot(s) were not decided. However, other relievers to see action will be Kendall Graveman, Kenan Middleton, Casey Sadler, and Will Vest. All could see plenty of action if the starters struggle early.


The Mariners front-office personnel are confident that they are building a solid organization. The team currently has a top-five ranked farm system. They have started to find and move in pieces for their core on offense. Fans are hoping the team could be a surprise contender in 2021. However, it is more likely that their time will come in either 2022 or 2023 as their players are developed and gain experience.

Main Photo:

Embed from Getty Images

Players/executives mentioned:
Jerry DiPoto, Mitch Haniger, Kyle Lewis, Kyle Seager, Evan White, J.P. Crawford, James Paxton, Justin Dunn, Chris Flexen, Yusei Kikuchi, Justus Sheffield, Marco Gonzales, Rafael Montero, Anthony Misiewicz, Nick Margevicius, Kendall Graveman, Kenan Middleton, Casey Sadler, Will Vest

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