Seattle Mariners: 3 biggest weaknesses going into the 2021 season

The Seattle Mariners have had quite the offseason after finishing 27-33 in the shortened 2020 season. It started peacefully, as players like Dee Gordon and Yoshisha Hirano were not brought back on new deals, and then Seattle made a slew of intriguing signings like Chris Flexen, Ken Giles, Keynan Middleton, and James Paxton.

Their offseason was quiet, too quiet. All of a sudden, the bombshell of the Kevin Mather news struck the Mariners’ world, and then even the baseball world as a whole. Within a few days that included zero signings or trades, this winter became the most memorable Mariners offseason that the franchise has ever had.

With all of that aside, let’s look at the team’s weaknesses from last season. The biggest one was the bullpen, as the Mariners had the third-worst bullpen ERA in the majors at 5.92, and if it were not for historically bad Phillies and Rockies ERA’s it would have been the worst.

So to combat that, Jerry Dipoto went on a mission signing Ken Giles and Keynan Middleton as well as trading for Rafael Montero. Is that enough to get the bullpen off of this list? The Mariners also had the third-worst OPS in the MLB and did not make any major league signings to address it. But, does that mean hitting makes it onto this list? Well sort of.

So, without further adieu, let’s get to it and see what Seattle has to improve upon next season.

What are the Mariners’ 3 biggest weaknesses going into the 2021 season?

Hitting vs Left-handed pitching

What a lot of people thought the Mariners needed this offseason was more left-handed hitting. However, if you take a deeper look into the stats and what the future looks like for the Mariners lineup, it becomes more clear that what Seattle really needs is more right-handed hitting, or lefties who can hit left-handed pitching.

Seattle was the worst hitting team against left-handed pitching last year. In 2020 the Mariners finished last in the MLB in OPS against left-handed pitching at .609. They also ranked last in batting average, last in on-base percentage, and second to last in slugging all against left-handed pitching.

While they did nothing to address this, they do have Mitch Haniger and Tom Murphy returning who both missed all of last season and are both excellent hitters against lefties. However, here is how the Seattle Mariners fared against left-handers last season in terms of OPS, with players whose OPS vs. lefties was worse than vs. righties in bold.

C Tom Murphy: 1.103 (2019)

1B Evan White: .462

2B Dylan Moore: .762

3B Kyle Seager: .649

SS JP Crawford: .661

LF Fraley, Trammell, and Kelenic are all left-handed hitters

CF Kyle Lewis: .805

RF Mitch Haniger: .829 (Career)

DH Ty France: .630, Jose Marmolejos: .551

The moral of the story, the Mariners will most likely struggle again next season against left-handed pitching. Haniger and Murphy will help, but I don’t see them moving Seattle out of the bottom 5 in OPS vs left-handed pitching.

The Bullpen

Despite General Manager Jerry Dipoto’s efforts to make the Mariner bullpen something that it was not last season, which is just an average or servicable bullpen, it still looks like it will be one of the major weaknesses of this team.

Ken Giles, who was the biggest signing for the bullpen, will not pitch this year. Keynan Middleton, the other major league signing for the bullpen, has allowed 8 earned runs in 4 innings this spring, and Rafael Montero, who the Mariners traded for, has pitched 3 innings and has allowed 4 earned runs.

Roenis Elias was looking fantastic and was most likely on a path to be put on the 40 man roster and maybe even the MLB roster, but he just had surgery and will miss some time. The Mariners also invested their Rule 5 draft selection in reliever Will Vest, who has been shaky this spring and if Spring Training ended tomorrow, I would say he would be sent back to his original team, the Tigers.

Of course, it is just spring and there have been some good performances out of the pen, but the bullpen is not looking great, especially the new arms on major league contracts. It will be better than last year’s pen, but I wouldn’t expect it to transform into one of the better bullpens in the American League.