The Mariners remain the only franchise never to reach the World Series, but their immediate challenge is more modest -- and more attainable. A repeat as American League West champions would represent new ground for Seattle, as well as an important checkpoint for a club looking to build on a 2025 season that ended one win shy of the Fall Classic.
On paper, the Mariners have the most talent of any team in the division. That said, the Astros and Rangers aren’t going away, and the improving Athletics add another potential obstacle for Seattle.
As the Mariners prepare to vie for a second straight AL West crown, let's take a look at three factors that could define their quest.
1. Production of young infielders
With first baseman Josh Naylor, second baseman Jorge Polanco and third baseman Eugenio Suárez all reaching free agency, the Mariners entered the offseason facing significant questions across the infield. Though Seattle moved quickly to re-sign Naylor for $90 million on a five-year deal, the club lost Polanco to the Mets. Suárez, meanwhile, is still unsigned.
A Suárez reunion shouldn’t be ruled out, but as it stands, the Mariners appear poised to have a trio of unproven youngsters -- 20-year-old Colt Emerson (MLB Pipeline’s No. 9 overall prospect), 22-year-old Cole Young and 25-year-old Ben Williamson -- compete to fill the club’s openings at second and third base.
2. Health of starting pitchers
Seattle’s stable of controllable starters has been perhaps the team’s greatest advantage in recent years. But 2025 showed that even elite rotations are not immune to setbacks. Injuries limited the trio of Logan Gilbert, George Kirby and Bryce Miller to 66 starts, over which they posted a combined 4.30 ERA. It was a noticeable step back from 2024, when they made 97 starts with a 3.24 ERA.
The Mariners did have those three healthy for the playoffs, but they lost Bryan Woo -- their best starter all year -- to a right pectoral injury in September and only got him back for a pair of relief appearances late in the ALCS. There are also reasons to be concerned about Luis Castillo -- the righty has made at least 30 starts in each of the past three years, but he’s entering his age-33 season and has seen his strikeout rate sharply decline in each of the past two years.
3. The Big Dumper's encore
Cal Raleigh just put together one of the greatest catching seasons in MLB history, breaking numerous records and finishing second to Aaron Judge in the AL MVP race. The Mariners needed every bit of the backstop's 60 homers, .948 OPS and 9.1 fWAR to win the AL West, as they didn't clinch the division crown until Game 158.
Raleigh was already one of the game’s best catchers before 2025, averaging roughly 30 homers and 4.6 fWAR per year across ’22-24, but he was on a completely different level last season. Replicating that performance is going to be a tall task, but if the aforementioned factors don’t go the Mariners’ way, they might need Raleigh to come close to maintain their edge in the AL West.