Seattle Mariners 2021 Season Preview

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       For the Mariners\’ standards, this was a quiet offseason. GM Jerry DiPoto is known to get trade-happy, but he stayed pretty quiet. This rebuilding team was able to stay out of the headlines and work on developing their team for the future, until Kevin Mather stepped in. The team president said a lot of revealing things on a rotary club meeting, which led to his resignation. But as Mather promised during that meeting, the future is bright in Seattle.

Offseason additions: LHP James Paxton, RHP Rafael Montero, RHP Ken Giles, RHP Chris Flexen, RHP Keynan Middleton, 1B Sam Travis, LHP Roenis Elias.

Offseason subtractions: IF Dee Strange-Gordon, RHP Yoshihisa Hirano, OF Phil Ervin, UT Tim Lopes, RHP Bryan Shaw, LHP Nestor Cortes Jr.

Trade Deadline 2020 summary

Acquired: IF Ty France, C Luis Torrens, OF Taylor Trammell, RHP Andres Munoz, OF Alberto Rodriguez.

Traded: C Austin Nola, RHP Taijuan Walker, RHP Austin Adams, RHP Taylor Williams, RHP Dan Altavilla. 

2020 record: 27-33

2020 placement: 3rd

2020 WAR leader (batter): Dylan Moore

2020 WAR leader (pitcher): Marco Gonzales

Starting Pitchers

The Mariners have been in clear support of a 6-man rotation entering the season, and that will mean a three-man bench. A perfect mix of prospects and veterans will be achieved throughout the year, as young players move up through the minors. Marco Gonzales is in the middle of those two groups, as he is not a prospect at age 29, but he is also entering just his fourth full season, so I would not declare Gonzales a veteran yet. In 69.2 innings last year, he had 64 strikeouts, for a career high 8.3 K/9. What Gonzales lacks in strikeout power, he made up for it with a 3.10 ERA and a 0.947 WHIP. He is a master of control, with just a 2.5 BB% and a 0.9 BB/9 in 2020, the latter leading the league. Returning to Seattle after a two-year stay in New York is James Paxton, who noticeably saw his fastball velocity fall off, which is a massive concern. After average over 95 mph and touching 97 in 2019, Paxton was sitting 92 last year. He was still able to strike out 26 in 20.1 innings, but Paxton had a 6.64 ERA and a 1.475 WHIP through five starts before missing the rest of the season with an injury. The main player acquired for Paxton back in the November 2018 trade was Justus Sheffield, who was productive in 10 starts as a 24 year old last year, but with some flaws. Sheffield had a 3.58 ERA with 48 strikeouts and just two home runs in 55.1 innings, but batters hit him hard, with a 46.6 hard hit percentage. Sheffield\’s slider had a 47.5 percent whiff rate in 2019, but that fell to just 28.1 last year. He made up for that by allowing less hits, as the average against the slider dropped by over 100 points, down to .192. Yusei Kikuchi had a rough season while adapting to North American baseball in 2019, but showed some more promise last year. Yes, Kikuchi had a 5.17 ERA with 47 strikeouts in 47 innings. But, he had a 7.9 H/9, while lowering his xERA to 3.37. Kikuchi was also able to limit batters to a .321 xSLG. There is a chance that the only right-hander in the Mariners rotation is Chris Flexen (yes, you read that right, Mets fans). Flexen had an 8.07 ERA in 68 innings over three seasons as a Met from 2017 to 2019, but decided to go to the KBO for 2020. It obviously worked, as he got an MLB deal. In 21 starts, Flexen had a 3.01 ERA with 132 strikeouts in 116.2 innings. The last rotation spot is between Justin Dunn, a righty, and a southpaw in Nick Margevicius. Both spent significant time in last year\’s rotation, but Dunn is the favorite, as he has more potential, and was a little bit better. A 2016 first round pick of the Mets, Dunn had a 4.34 ERA with 38 strikeouts in 45.2 innings. Control was a big issue for him, as he walked 31 batters, or 15.7 percent. Batters also hit Dunn hard, with an average exit velocity of 92 mph. Margevicius could end up in the bullpen is he does not make the rotation. He had a 4.57 ERA in 41.1 innings after being claimed off waivers from San Diego. Walks were not as much of an issue for him as they were for Dunn, and Margevicius had a better xERA of 4.36. We could also see 23 year old Logan Gilbert pretty soon. A first rounder in 2018, Gilbert reached AA in 2019, and in the minors in total, he had a 2.13 ERA with 165 strikeouts in 135 innings.

Relief Pitchers

The Mariners had an awful bullpen last year, and their new closer is Rafael Montero (yes Mets fans, you read that right again), who saved games for Texas last year. Montero had eight saves while striking out 19 in 17.2 innings with a 4.08 ERA. The highest average against one of Montero\’s four pitches was .200. Despite throwing a sinker almost a quarter of the time, Montero had a very low groundball rate of 28.9%. He actually allowed more line drives than ground balls. The best Mariners reliever last year was easily Yohan Ramirez, a 25 year old who in his rookie season posted a 2.61 ERA with 26 strikeouts in 20.2 innings. Batters had just a .149 xBA and a .279 xSLG against Ramirez. Batters went just 1-for-32 with an 81.8 mph average exit velocity and a 42.9 percent whiff rate against his slider. The Mariners have seen Keynan Middleton over the past few years as a member of the rival Angels. He allowed one run in 7.2 innings in 2019 while returning from Tommy John surgery, but his velocity was down. That came back up to 97.1 mph on average last year, but his overall numbers worsened. Middleton allowed seven earned runs in 12 innings. Also returning from TJ surgery was Kendall Graveman, who can start games, but mostly came out of the bullpen in 2020. He had a 5.79 ERA in 18.2 innings, but at 3.68, Graveman\’s xERA was much better. Despite allowing a 91.6 mph average exit velocity, batters had just a .229 xBA and a .359 xSLG against Graveman. Casey Sadler had a 2.14 ERA in 33 games in 2019, but struggled last year for the Cubs and Mariners. In Seattle, Sadler had a 4.50 ERA with 12 strikeouts in 10 innings. His walk rate went up by over seven percent, up to 14%. Still, Sadler allowed a hard hit percentage of just 26.4 percent, and his 2930 rpm curveball had a 44.4 percent whiff rate. Anthony Misiewicz was a starter in the minors, but transitioned into a one inning reliever at the big league level. He struck out 25 with a 4.05 ERA in 20 innings, and allowed just one barrel all year. Misiewicz had a 3.37 xERA, and batters went 1-for-10 against his mid-90s fastball. Matt Magill struck out 28 with a 3.63 ERA while saving games down the stretch in 2019, but struggled in Seattle last year. He had a 6.10 ERA with an average exit velocity of 91.1 mph. Both his slider and curveball can get whiffs. 23 year old Joey Gerber was a strikeout machine in the low levels of the minors, but had just six in 15.2 innings in 2020, his first MLB season. Gerber had a 4.05 ERA, and could benefit from some more time in the minors.


The Mariners have seen Omar Narvaez and Austin Nola leave via trade in recent seasons, but they still have a good offensive bat in Tom Murphy, who was a breakout player in 2019. However, a broken foot cost Murphy all of 2020. He hit 18 home runs in 75 games in \’19, with an OPS of .858. There were some flaws, however, as Murphy struck out 31 percent of the time. He will split time behind the plate with Luis Torrens, a former Rule-5 pick acquired in the same deadline deal that sent Nola to San Diego. In 18 games after the trade, Torrens had a .696 OPS. He is not the best defensive catcher, so the 24 year old could use some work there. 


Evan White had his rookie season in 2020, and he is a very interesting first baseman. He may already be the league\’s best defensively, with six outs above average last year, and a Gold Glove. But, White is also a well below-average hitter, at a position demands offensive skill. White struck out a whopping 41.6 percent of the time, with eight home runs, a .176 average and a .599 OPS. White can hit the ball well, with a 14.7 barrel percentage and a 91.7 mph average exit velocity. Dylan Moore led the team in WAR in 2020 after a rough rookie season in 2019. He can be a super utility player, or start at second base. Moore hit eight home runs while stealing 12 bases with an .855 OPS. Moore lowered his strikeout rate, but at 27% it is still a problem. He played all seven infield and outfield positions last year. A former top prospect of the Phillies, JP Crawford has never been able to get it going offensively. He had an 85.8 mph average exit velocity with a .674 OPS in 2020. He stole six bases, but Crawford\’s 26.6 ft/s sprint speed was below average. Where Crawford really excelled was defensively, with seven outs above average, as he came home with his first Gold Glove. Kyle Seager is entering his 11th season as a Mariner, and it could be his last, especially if Kevin Mather was not lying. Seager had a 122 OPS+ last year while playing in all 60 games. The former was his highest since 2016. While striking out just 13.3 percent of the time, Seager hit nine home runs with a .788 OPS. He also had two outs above average, and his walk rate was a big improvement at 12.9 percent. Shed Long was the team\’s main second baseman in 2020 after he had a .787 OPS in 2019. Long slumped throughout 34 games last year, with a .173 xBA, a .301 xSLG and a .533 OPS. He also had -3 outs above average at second base. Long had surgery in the offseason, and could start as a backup infielder. Another backup infielder possibility is Sam Haggerty, who stole four bases in 13 games for the Mariners last year. Ty France can be the normal DH, but also play third base. Despite getting traded mid-season, France was solid offensively throughout, with a total of four home runs, a .305 average and an .836 OPS in 43 games. France had a .285 xBA, but had an average exit velocity of just 85.7 mph. 


While the Mariners have a ton of up-and-coming outfield prospects, Kyle Lewis asserted himself as the starting center fielder, by winning AL Rookie of the Year. He hit 11 home runs while stealing five bases with an .801 OPS. Lewis walked 14 percent of the time, but also struck out an additional 29.3 percent of the time. He had two outs above average in center. The only other lock in the outfield is Mitch Haniger in right field. Haniger was an all-star in 2018, but missed most of 2019 and all of 2020. In 63 games in 2019, Haniger had a .778 OPS with 15 home runs. Haniger is healthy now, and so far in Spring Training, he is 6-for-22 with a home run. The left field starter is up for grabs, and because of the six-man rotation, only one player who misses out can make the team as a backup. Jose Marmolejos hit 16 home runs with a .315 average and a .912 OPS in 101 AAA games in 2019, and played in 35 games last year. Marmolejos hit six home runs with a .672 OPS. He struggled against breaking balls and offspeed pitches, but crushes fastballs. Marmolejos hit five home runs with a 95.1 mph exit velocity against heaters last year. He can play corner outfield as well as first base. Taylor Trammell is still a highly-rated prospect, but his stock has fallen off since switching teams twice. In AA in 2019, Trammell stole 20 bases but had a .689 OPS. In 11 Spring Training games so far, Trammell has a .292 average with a .954 OPS. Jake Fraley has a .427 OPS in 19 career games, but he hit 19 home runs with 22 stolen bases and a .910 OPS between AA and AAA in 2019. He has gone just 4-for-25 this spring. Top prospects Jarred Kelenic and Julio Rodriguez will be options soon, but not now. 

Projected Rotation
Marco Gonzales (L)
James Paxton (L)
Justus Sheffield (L)
Yusei Kikuchi (L)
Chris Flexen (R)
Justin Dunn (R)
Projected Bullpen
Rafael Montero (R)
Yohan Ramirez (R)
Keynan Middleton (R)
Kendall Graveman (R)
Casey Sadler (R)
Anthony Misiewicz (L)
Nick Margevicius (L)
Matt Magill (R)
Projected Lineup
2B Dylan Moore (R)
CF Kyle Lewis (R)
RF Mitch Haniger (R)
3B Kyle Seager (L)
DH Ty France (R)
C Tom Murphy (R)
LF Jose Marmolejos (L)
SS JP Crawford (L)
1B Evan White (R)
Projected Bench
C Luis Torrens (R)
IF Shed Long (L)
OF Taylor Trammell (L)


I have been a big fan of what the Mariners have been doing with their most recent rebuild, and they have made some nice trades during their blow-up. The bullpen still needs a lot of reconstruction, but the rotation and lineup are solid. The Mariners are a fourth place team, but hopefully they will end their playoff drought soon. 

Published by carterhud SI Kids Kid Reporter, Prime Time Sports Talk writer

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