Top Mariners Spring Training Storylines to Follow

Coming into the 2026 season, the Mariners are going to want to hit the ground running.

Despite the tough finish to their 2025 season, the Mariners have quite a bit to be excited about. This upcoming season is one of the most anticipated in franchise history, and for good reason.

The Mariners went 90-72 in 2025, and their first-place finish in the AL West last year bodes well for their playoff odds this year. They’ve added some significant pieces in the offseason, and are relatively healthy despite a few injury hiccups.

In order to punch their franchise’s first ticket to the Fall Classic, the Mariners are going to have to count on standout performances around the roster. The starting rotation is still projected to be elite, but they will still have to tinker a bit.

George Kirby is coming off of a down year by his standards, and with Bryce Miller’s oblique issue continuing to bother him, others will have to step up. Bryan Woo and Logan Gilbert will be able to lock down the front end of the rotation. Cooper Criswell has looked great, but Luis Castillo will have to figure something out before Opening Day.

As for the offense, the lineup should get better naturally with their offseason additions. Curtain calls for Cal Raleigh and Julio Rodríguez are in order, and steps forward from Dominic Canzone, Ryan Bliss, and J.P. Crawford would take the lineup from good to verifiably elite. 

The team still has a bit of time to get ready, but signs are mostly positive for the Mariners going into this year. The final stretch of spring training will be crucial in finalizing roster construction and establishing a baseline to start the year. However the team may look come Opening Day, the stakes will be very high from here on out.

New and Returning Faces

The Mariners’ re-signing of Josh Naylor and trades for Brendan Donovan and Jose A. Ferrer provided Seattle with a well-needed boost going into 2026.

Naylor has been one of the most consistent hitters in baseball since 2022, and he hit great down the stretch for the Mariners in 2025. Over 54 games, Naylor hit .299/.341/.490 with 9 homers and 33 RBIs. He was also a pivotal part of their ALCS run, hitting three home runs with a 1.273 OPS.

The Mariners signed Naylor to a five-year, $92.5 million contract in the offseason, bolstering their long-term lineup considerably. They also strengthened their lineup further with their trade for Donovan from the St. Louis Cardinals.

Donovan still has several years of team control remaining, and has been a remarkably consistent hitter since his debut. He also provides strong utility around the infield and occasionally corner outfield positions. While his main home might be second base, the Mariners are expected to shuffle him around the field.

So far in spring training, Donovan has hit .452/.514/.516 for the Mariners over 35 plate appearances. Small sample or not, he has quickly endeared himself to Mariners fans, and his success bodes well for the Mariners’ offense going into the 2026 season.

Ferrer’s early spring training performance has been a mixed bag. Over 4.2 innings, Ferrer has allowed six hits and two walks, leading to five earned runs. Still, the 26 year-old southpaw figures to be a strong addition to the Mariners’ bullpen.

Acquired from the Washington Nationals this winter, Ferrer is adept in limiting traffic on the basepaths and preventing home runs. He primarily leans on his high-90s sinker, a changeup, and he mixes in a slider against lefties. 

If the Mariners can further develop his arsenal, Ferrer can provide Seattle with a much-needed left-handed option to complement Gabe Speier in the later innings.

Pitching Factory

The Mariners boast one of the best pitching development systems in professional baseball. Seattle has had a top-shelf starting rotation for years now, and based on what they are showing in spring training this year, they have reinforcements on the way.

Two of their top pitching prospects, Kade Anderson (JB No. 26) and Ryan Sloan (JB No. 29), have shown impressive potential so far in camp. Neither is expected to get a ton of reps during big-league camp, but their reception has been incredibly positive among the organization.

When asked about the two of them, the Mariners’ president of baseball operations Jerry Dipoto spoke very highly of the pair. He commended their consistency and maturity, and noted, “I don’t imagine either one of them is going to spend a heck of a lot of time in the high minors.”

Anderson and Sloan have compiled 7.0 and 1.0 innings, respectively, so far in spring training. Despite the small sample size, both players have shown a flash of what they are capable of.

Stuff models are somewhat skeptical of Anderson’s fastball, but his deceptive delivery and wide arsenal are likely to translate to big-league success. Conversely, stuff models are far from skeptical of Sloan’s arsenal.

Sloan struck out one batter and did not allow a baserunner in his short outing. He touched 98.9 mph on his fastball and generated impressive break on his secondaries while averaging 6.8 feet of extension.

He spins the ball well, and at just 20 years old, he will have plenty of time to develop. Sloan’s promising spring debut indicates that he has a rock-solid foundation to build upon. Between Anderson and Sloan, the Mariners have one of the best tandems of pitching prospects in MLB coming through the pipeline.

Emerson vs. Young

One of the more interesting developments for the Mariners in spring training is the battle to lock in the starting infielders.

Both players figure to be a significant part of the Mariners’ potential success in 2026. However, the question of which player will become the Mariners’ starting second baseman makes for a very difficult decision.

Colt Emerson, the Mariners’ first-round draft pick in 2023 and Just Baseball’s No. 5 overall prospect, has quickly ascended through the minors. While early spring training stats may not be all that glamorous, he has quickly become the Mariners’ top prospect at just 20 years old. Emerson boasts a smooth left-handed swing and has showcased solid defense across multiple infield positions.

The case for Emerson to crack the starting roster is not yet set in stone. He is blocked by J.P. Crawford at his natural position — shortstop — and the addition of Donovan will mean more competition at both second and third base.

Yet, despite this, Emerson’s biggest competitor may be the Mariners’ first-round draft pick from the year before his selection. Cole Young played in 77 games for the Mariners in 2025. At just 21 years old, his performance left room for improvement, as it culminated in a .211/.302/.305 slash line.

This spring training, however, something seems to have clicked for Young.

He’s hit four homers over his 46 plate appearances, and he is currently sporting a .982 OPS. Young did get off to a pretty cold start to camp but has looked much better as of late.

The starting gig is Young’s to lose for the time being. Depending on the status of shortstop J.P. Crawford, Emerson may start the year in Triple-A. Still, fans can expect to see him in the majors sooner rather than later.