Seattle Mariners 2023 Season Preview
One of baseball’s best stories was written in the Pacific Northwest last season. The Seattle Mariners ended a 20-year playoff drought in epic fashion on Cal Raleigh’s pinch-hit walk-off home run on Sept. 30. Just to make it a little sweeter, they went on the road in the Wild Card Round against the Blue Jays and won the best-of-three series in two games, erasing a seven-run deficit in the process for the decisive Game 2 victory.
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The storybook didn’t happen, as the Mariners lost a devastating 1-0 decision in 18 innings to get swept by the Astros in the ALDS, but the team got over a huge hump and the roster looks even better for 2023. The ALDS also could’ve gone very differently. Scott Servais inexplicably went to Robbie Ray in the ninth inning of Game 1 and Yordan Alvarez hit a ball that broke the sound barrier for a walk-off three-run homer. Game 3 could’ve fallen any number of ways. They were right there against the eventual World Series champs, a team they finished 16 games behind in the division.
Being “right there” has mostly evaded the Mariners. They’ve won 90 games in back-to-back seasons for the first time since 2002-03 and this is the first time they’ve had consecutive winning seasons since then. Jerry Dipoto’s seemingly endless games of musical chairs finally brought the right combination to Seattle and last season may have been just the beginning.
Explanations of the stats used in this preview can be found in my “MLB Stats to Know” article.
2023 Seattle Mariners Odds
(odds from DraftKings as of Mar. 10, click for updates)
World Series: +1800
AL Pennant: +850
AL West: +310
Win Total: 87.5 (-115/-105)
Make Playoffs: Yes -165 / No +135
Seattle Mariners Offense
The Mariners had a top-10 offense last season and look poised to be as good or better this season. They’ve upgraded at second base with Kolten Wong over Adam Frazier and moved on from Jesse Winker and Mitch Haniger with Teoscar Hernandez. This will be a big year for Jarred Kelenic, but the Mariners have good depth and good star power in the lineup to pair with one of my favorite pitching staffs in the league.
Obviously any breakdown of the Mariners should start with a focus on Julio Rodriguez, who will go from winning the AL Rookie of the Year to challenging for the AL MVP. He missed a little bit of time in early August and again in September, but led with 5.3 fWAR and a 146 wRC+. I hesitate to use “can’t-miss prospect” in baseball because so many things can go wrong, but Rodriguez has been destined for greatness and he’s on his way. He’s also signed through 2029, so the Mariners have their cornerstone superstar.
I think he’s poised for a better season as well. His 25.9% K% was higher than any level of the minors and above what his contact tool was projected to be. He also only walked 7.1% of the time. I would anticipate better plate discipline from him now that he’s more familiar with the league’s pitchers. As it is, he went from a 136 wRC+ in the first half to a 169 wRC+ in the second half and cut his K% nearly 3%.
The supporting cast for J-Rod is still strong, as Eugenio Suarez and Ty France combined for 51 homers and around a 130 wRC+. J.P. Crawford walks at a high rate and still had a 104 wRC+ despite a .275 BABIP. The aforementioned Raleigh is a solid defensive catcher and an above average hitter. Wong does represent a big upgrade over Frazier, as he posted a 117 wRC+ to follow up his 110 mark in 2021. Frazier had an 81 wRC+, so that means roughly a 30% increase in offensive production at second base.
Hernandez has been an above average hitter each of the last six seasons, posting wRC+ marks of 132 and 129 the last two seasons. He does decline in park factor a bit here, but he makes extremely violent contact with an elite Hard Hit%. I even like AJ Pollock as a super buy-low guy. The White Sox were toxic last season and he had been above average by wRC+ for five straight seasons and seven of the last eight. The one where he wasn’t only featured 46 plate appearances. He’s on the wrong side of 35, but he can DH and play the OF to spell guys. He had a 92 wRC+ last season and now has a much better situation.
Dylan Moore got paid this winter with a three-year extension after a surprising 126 wRC+ and 2.1 fWAR as a part-timer. Sam Haggerty was also limited, but produced when called upon. This is a deep, talented, balanced and quietly improved position player group. The Mariners were 23rd in Hard Hit% last season and still had a top-10 offense. I bet they move up that leaderboard this season.
This is actually one of the deepest lineups in baseball. If Pollock returns to form and Kelenic showcases the skills that made him a highly-touted prospect, we’re talking about a lineup where every hitter will be league average or better. And, if it’s not Pollock or Kelenic, Tommy La Stella, Moore and Sam Haggerty are really nice bench pieces. I’m low-key in love with this position player group.
Seattle Mariners Pitching
Normally I begin with the starting rotations first, but I have to start with the bullpen here. I do like the rotation, but this bullpen has insane upside. A left-handed reliever will emerge during camp, but there are some power arms with some sick stuff at the back end of this relief corps. Seattle’s pen had the lowest Hard Hit% against at 32.9%, which was over a full percent better than anybody else. They had the lowest exit velocity against at 86.8 mph.
This was a group that was fifth in K%, fifth in BB% and got a little unlucky in the home run department. Paul Sewald and Andres Munoz took turns being unhittable. Penn Murfee and Diego Castillo are hard to hit. It looks like Matthew Festa and Matt Brash will vie for the high-leverage innings that used to go to Erik Swanson, who is now with the Blue Jays from the Hernandez deal. This is a strong unit and Scott Servais deployed his arms well, at least until Game 1 of the ALDS.
The addition of Luis Castillo certainly helped the Mariners and they’ll have him for this season and beyond, but George Kirby is the guy that stood out to me. Kirby only allowed one home run in the second half over 65.2 innings. He went from a .327 wOBA against to a .278 wOBA against, with the huge decrease in HR as the primary reason. He actually didn’t generate a lot of swing and miss on his secondaries, but his high-velocity fastball and ability to use it up in the zone helped overcome that shortcoming.
I would also anticipate he’s learning more about his secondaries, especially his slider. A guy that knows about sliders is Castillo, who had a 3.17 ERA with a 2.91 FIP in 65.1 innings with the Mariners. He’s been borderline elite in a bad pitcher’s park throughout his career and was a terrific acquisition for Seattle. I’d expect him to be one of the AL’s best this season. The shift ban may hurt him as an extreme ground ball guy, but I think we see him go for more strikeouts as a result. He can do it, too.
Admittedly, Logan Gilbert scares me because of a high Hard Hit% of 45.6%, but he works around it pretty well. His fastball velocity in the 87th percentile coupled with 99th percentile extension means that the ball gets on hitters very quickly. I do think the Mariners continue to focus on upper-quadrant fastballs while refining breaking stuff a bit to generate more swing and miss. This is also a good defensive team, especially in the outfield.
Playoffs aside, Robbie Ray had a good season with a 3.71 ERA and a 4.17 FIP in his first year as a Mariner. It wasn’t his fault that he got thrown into an awful Game 1 situation as a guy with huge home run issues against one of the league’s best power hitters. I think he’ll reliably eat up 190 innings and be just fine. I can’t say the same for Marco Gonzales, but he is what he is and can survive at home like he did last year.
Top to bottom, I like this pitching staff a lot and the Mariners are doing a really good job as an organization and I like the job that pitching coach Pete Woodworth is doing.
Miscellaneous Notes
Seattle’s bullpen advantage was on display a lot last season, as they went 34-22 in one-run games. They did overperform relative to BaseRuns record, finishing +5 games, but bullpen dominance is part of that equation. They also performed at their best as a pitching staff with men in scoring position, holding opponents to a .288 wOBA. Only the Dodgers and Astros were better in that split.
The Mariners were only 21-28 through 49 games. They went 69-44 the rest of the way, which is a .611 win percentage and a pace for 99 wins in a full 162-game season.
Player to Watch
SP George Kirby: What really stands out about Kirby to me is that his platoon splits were crazy. Lefties had a .245 wOBA against him in 284 plate appearances, but righties crushed him with a .366 wOBA in 258 PA. You typically see the opposite in right-handed pitchers, but that was not at all the case with Kirby. His K% was much higher against lefties and righties hit a much higher rate of homers. What makes this even more interesting is that Gilbert had similar splits, as lefties had a .256 wOBA in 348 PA and righties had a .334 wOBA in 418 PA, hitting 14 of the 19 homers he allowed. If the Mariners figure this out, they have a potentially dominant rotation.
Seattle Mariners Season Win Total Pick
It would be an exaggeration to say that I’m all in on the Mariners, but I love this team. I’ve been on the fence about a few win total bets for one reason or another, but this isn’t one of them. This team is winning 90+ games. This is a deep team with a general manager that has finally played enough “Franchise Mode” to get everything exactly where he wants it. There really aren’t any weak links and this is a lineup capable of withstanding the inevitable injuries that come along with an MLB season.
Something else to keep in mind about the Mariners is that Dipoto profiles as a very aggressive GM at the Trade Deadline. If this team is in the hunt, they’re going to get some help. He got Castillo this past season, who helped break the long playoff drought. I think they feel like this is the time to go for it and the closely-played series against the Astros was an affirmation that they are right there amidst the AL’s best.
I don’t know if I have the wherewithal to take this team at +310 to win the AL West, but I think they’ve got a shot, despite finishing 16 games behind Houston last season. But, I do think this team is poised to win 90 or more games for the third straight year and this is my favorite season win total wager in the American League.
Pick: Over 87.5
