The Seattle Mariners enter their 2026 Major League Baseball (MLB) campaign carrying the expectations that come with finally breaking through. After winning the AL West in the 2025-26 season, and falling one win short of reaching the World Series, the Mariners opened this season in March with a roster that, on paper, looks deeper and more complete than any in recent franchise history. The early returns, though, are a reminder that baseball rarely follows a script.
Seattle finished its opening homestand at 3-4, splitting four games with the Cleveland Guardians before dropping two of three to the New York Yankees. Even so, the larger picture around the club has not changed much. MLB.com’s season preview described the Mariners as a team with “virtually no question marks” on the roster, highlighted by five recent All-Stars and a rotation capable of being baseball’s best. The biggest question remains health, especially after Bryce Miller opened the season on the injured list.
That belief in the roster showed up in comments from majority owner John Stanton ‘77, who said the optimism inside the organization is rooted less in last year’s success than in the players themselves.
“I think it’s not the momentum or success from last year,” Stanton said in an interview the day after opening night. “It’s always about the players. And we had a terrific group of players last year. They’re generally very young. I think most of them are going to continue to get better.”
The two biggest additions to the Mariners roster are first baseman Josh Naylor and third baseman Brendan Donovan. Naylor was acquired in July 2025 in a trade with the Arizona Diamondbacks, and Donovan in a three-way trade between the Mariners, St. Louis Cardinals and Tampa Bay Rays. Naylor has struggled to find his offensive footing in the lineup but has maintained a fielding percentage of 1.000. Donovan came out swinging as an offensive threat, hitting a leadoff home run during the Mariners season opener and batting .417 as of April 2.
“We gave up some really good young players that we were excited about in [the Donovan] trade,” Stanton said. “But we feel pretty good about the role he’ll play, probably a little better about him after he had a leadoff home run last night.”
Stanton believes that youth is central to Seattle’s identity. Center fielder and perennial All-Star candidate Julio Rodríguez is still only 25. Catcher Cal Raleigh, coming off an MVP-caliber breakout season, remains one of the faces of the franchise at 29. Infielder Cole Young, just 22, already looks comfortable in the majors, batting .320 and providing the Mariners a spark at the bottom of the lineup, while 26-year-old starting pitcher Emerson Hancock delivered six impressive no-hit innings in his first outing.
The Mariners’ opening weekend performance was uneven. Seattle’s offense sputtered in stretches, and by the end of the first week Raleigh, Rodríguez and Naylor had combined to hit just .090. Yet, manager Dan Wilson shared that he still felt good about where the season is heading.
“Obviously, you want to win more games in the opening part of your season here,” Wilson said. “But I feel good about the adjustments we’re making and the direction we’re heading.”
Stanton repeatedly returned to one theme when discussing why he believes this group can steady itself: culture.
“The culture really belongs to the players,” Stanton said. “We try really hard to make sure that the right guys are in the room.”
Beyond collecting talent, that means building a clubhouse with the right leadership and accountability.
“You need someone who’s welcoming players onto the team,” Stanton said. “You also need someone who’s going to be the voice of holding people accountable.”
That is part of why Seattle valued roster additions like Naylor and Donovan. Stanton called both strong clubhouse fits and noted how easily the wrong personality can disrupt an organization.
“If you have someone who doesn’t represent the culture or the organization,” Stanton said, “they can really mess you up.”
That may be the most revealing part of Seattle’s season outlook. After all, the Mariners are no longer trying to convince themselves that they belong. Rodríguez believes that the club now has “a better understanding of who we are,” while Wilson pointed to last October’s playoff run as motivation for what comes next.
In addition to jelling their roster, the Mariners will also need to adapt to the MLB’s implementation of the Automated Ball-Strike (ABS) challenge system. This system allows batters, catchers and pitchers to challenge calls on balls and strikes. Each team is given two challenges per game, and a challenge is retained if successful. This ABS system forces pitchers to be more mindful of pitch placement — with umpires no longer able to expand the zone at the end of innings — and forces hitters to be more mindful of the edges and corners of the strike zone.
The season’s opening week was not smooth for the Mariners. But, for a team built on roster progression and with higher expectations than ever, the 2026 campaign still looks to be far more momentous than one uneven homestand.
