7 Mariners Storylines to Watch this Spring

What to watch for when you’re watching spring training.

With spring training getting underway in earnest with the first Cactus League games this weekend, now is as good a time as any to check in on the biggest and most important storylines surrounding the Mariners during the preseason.

How is the second base playing time going to shake out? How does Jorge Polanco look at third base?

The infield was the biggest area the Mariners needed to address this offseason, with holes everywhere except shortstop. They brought in Donovan Solano to act as a short-side platoon-mate for Luke Raley at first base and re-signed Jorge Polanco, not to play second where he’s played for the majority of his career, but to play third base. That leaves the keystone as the largest question mark in the lineup heading into the regular season.

By virtue of his seniority and proven production at the big league level, Dylan Moore will ostensibly get a shot to prove that he can handle a full-time role for the first time since the pandemic-shortened 2020 season. Moore may seem like a known quantity since he’s currently the longest-tenured player on the roster, but there were a few interesting changes to his approach last year.

Moore has always struck out a little too often to hack it as a big league regular but he managed to cut his strikeout rate by five points last year. Most of that improvement was due to a vastly improved 17.6% chase rate that sat in the 99th percentile in the majors and was nearly nine points lower than what it was in 2023. He also increased his contact rate to a career-high 78.1% and his zone-contact rate up to 85.7%, another career best. While his actual strikeout rate was still a little higher than you’d like, his peripherals indicated that that metric should have fallen even further than it actually did. If he maintains this new plate approach and continues to hit for some surprising power, it’s possible he could enjoy a breakout season as the Mariners full-time second baseman.

Of course, Seattle will also be evaluating Leo Rivas, Ryan Bliss, and most notably, Cole Young this spring to see if any one of that trio could take a big step forward and push Moore out of a full-time gig. Rivas is probably being counted on to backup all three high-skill infield positions and doesn’t have the pedigree to indicate he’d be all that valuable as a full-time player. Bliss looked promising in short spurts in his first exposure to the majors last year, but he was far too inconsistent to be really counted on. He did have some really encouraging batted ball peripherals — a 9.3% barrel rate and a 46.5% hard hit rate both standout — and his plate discipline should improve with more seasoning against big league pitching.

Young is the wild card. The Mariners already committed to keeping him down in the minors to start the season back in the fall, but he’s on the fast track to taking over as the second baseman of the future possibly as early as this year. If he has an outstanding spring training, the Mariners will face a lot of pressure to break camp with that future on the roster to start the season. The most likely outcome is that Moore holds on to the job with Rivas as the primary backup, while Bliss and Young continue to develop in Tacoma.

The related infield storyline to follow is watching how Polanco takes to his new role at third base. He does have about 180 innings at the position from his time in Minnesota so it’s not completely unfamiliar territory for him. It’ll be less of a strain on his knees and supposedly a better fit for his defensive range to his left, though his arm strength is a pretty huge question mark that will need to be answered. More than anything, we’ll want to see him healthy and moving without restrictions after a supposedly normal offseason following those recurring knee injuries that cropped up again last year. —JM

Are any pitchers tinkering with new pitches?

After a winter of tinkering, spring is the season where pitchers get to debut their new pitches against live competition. With a pitching staff filled with pitching nerds looking to hone and elevate their craft to the highest levels, it’s worth monitoring who is throwing something new and how that change could affect their entire repertoire.

Already we’ve gotten reports that Bryce Miller, George Kirby, and Emerson Hancock are trying out new cutters this spring and Hancock is working on a sweeper as well. A cutter should help Miller and Kirby keep batters honest by giving them a slightly different look off their four-seam fastballs and Hancock simply needs to refine his secondary pitches in his arsenal to give him more weapons to attack batters with.

Logan Gilbert is also reportedly working on a new curveball similar to Miller’s revamped “deathball” that he debuted mid-season last year. Gilbert already tinkered with his curve last year and turned what had been a mediocre offering into an extremely effective pitch by adding a bit of velocity and a ton of horizontal movement to it. Miller’s “deathball” has both high velocity and breaks a lot more vertically than horizontally. Gilbert already throws a ton of pitches without a ton of horizontal movement, so we’ll have to see how this new vertically oriented curveball affects his whole repertoire.

For the trio of established starters — Gilbert, Kirby, and Miller — any new offering is going to need to be significantly more effective than what they’re already throwing and synergize with the rest of their repertoire to form a complete arsenal. Adding a new pitch isn’t simply a shortcut to improvement, but it is worth watching to see if it does give them an advantage. For Hancock, who is still developing as a pitcher, this kind of tinkering is a good sign that he’s working to find a pitch mix that maximizes his skills and talent. —JM

Does the new hitting staff change the Mariners approach at the plate?

After his brief interim stint as hitting coach at the end of last season, the Mariners promoted Edgar Martinez to senior director of hitting strategy and hired Kevin Seitzer to run the day-to-day operations of the hitting program. Under their watch, the position player group will need to figure out how to translate their hot finish to last season into season-long production in 2025. There have been rumblings about the coaches’ desire to hone the team’s approach to focus on using the whole field and leaning on situational hitting to manufacture runs. Honestly, we probably won’t get any resolution to this storyline until the regular season is well underway, but it’s worth monitoring this spring to see if we can catch any glimpses of these new strategies. —JM

Can the Mitches show any signs of life?

I’ve lived what feels like a dozen lives with the Mitches. For Haniger, my affection is greater, longer lasting, and more painful to inspect. The last time Haniger was a quality big leaguer and hitter was 2022, and he missed almost two thirds of that campaign. He hit the ball hard still, but was swinging and missing more often than ever - and at pitches in the zone in particular he struggled, including fastballs which he’s historically mashed. It’s just not realistic that if this were any other player I would see reason to expect rejuvenation. I yearn for it, but I don’t expect it.

Garver, frankly, is more plausible. Last year was a disaster entirely for Garver, but he didn’t have physical declines in the same multi-year trend that’s seemingly observable in his fellow Mitch. Garver’s still all there, it’s just whether he can spoil more junk this season instead of pressing himself into waving weakly at it. I expect better, even if it’s not incredible. —JT

Which relievers from “the pile” will be spring standouts?

This year the pile looks a little different, as beyond the typical change-of-scenery/last-gaspers there’s a healthy infusion of homegrown pitching talent. Tall lefty Brandyn Garcia, who’d be in line for a bullpen role, probably gets the top votes staff-wide for the player we’re most excited to see, but watch out for Hunter Cranton, a 2024 draftee with a nasty fastball who will be a fast mover.

As for the rest of the pile, obviously there’s some intrigue around the hard throwers, most notably Shintaro Fujinama, who’s been clocked at 102.6, along with Dauris Valdez, who boasts upper level velocity along with a titanic frame. We are ardent admirers of the Mariners’ pitching development around here, but it’s a tough task to succeed where other teams have failed — remember the Big Mike Baumann experiment? — despite the tantalizing stuff.

But maybe the biggest bullpen storyline this year will be the improvement coming from players already in the organization. Ryan Divish reported that Gabe Speier is healthy and hitting mid-90s again, shaking off the injury that plagued him in 2024 and affected his velocity. Matt Brash is on track for a return in late April per Justin Hollander, and Gregory Santos has reportedly been impressive in his bullpen sessions. Being able to slot Santos or Brash — or in a perfect world, both — back into the back end of the bullpen, sliding everyone else down, and inserting the steady-hand Speier, would lift a bullpen that was middle of the pack by FIP last season. —KP

Do any key players on opposing teams get injured?

Yeah, not technically a Mariners storyline, but it feels extremely possible for the erstwhile Trader Jerry to jump on one of the inevitable Spring Training injuries and leverage that into another move just before the season starts. I don’t have much more to it than that. Their current rotation is exactly the same as it was last year and I’m feeling suspicious… —IM

Which hitters are going to round out the bench?

For better or worse, there figures to be very few roster spots truly up for grabs over the next five weeks, with backup/situational roles lacking the most clarity when it comes to the position players. With Donovan Solano seemingly destined for a role as Luke Raley’s right-handed platoon mate and Jorge Polanco’s backup/insurance policy at the hot corner, is the club really going to carry Austin Shenton (who I like!) just to be a left-handed bat off the bench? Or might the likes of Ryan Bliss, Leo Rivas, or Miles Mastrobuoni force their way onto the roster as an appealing baserunning option late in games?

And how about in the outfield? Is the club going to be comfortable choosing between their primary first baseman and a defensively declining Mitch Haniger as the fourth outfielder? I’d personally like to see Spencer Packard—whose shown a knack for drawing walks and avoiding strikeouts—get every chance to leapfrog fellow lefty-hitting outfielders Dom Canzone and Cade Marlowe as the “next man up” when it comes to filling the reserve outfield role.

Shoot, maybe Rowdy Tellez or Tyler Locklear randomly go “2009 Michael Wilson” and lead the team in home runs (he did) this spring and force their way onto the roster (he didn’t) at the expense of the Mitch-of-your-choosing’s DH at-bats. —BT