Biggest surprises, disappointments in 2025 Mariners' projected Opening Day roster

As the Seattle Mariners prepare for the 2025 season, their anticipated Opening Day roster reflects both strategic decisions and unexpected developments from spring training.​

While Ryan Divish of the Seattle Times didn't exactly spell out the Opening day roster this past Sunday, recent roster decisions give a pretty clear indication of what the team intends to do.

Biggest spring training surprises including a dominant Rowdy Tellez, an exciting utility man and the surprising Mitch Haniger decision

One of the biggest surprises this spring was a late addition on a minor league deal, as Rowdy Tellez didn't sign a minor league contract until February 21. From there, Tellez dominated the Cactus League, proving that he can be a productive hitter for a team starving for impact. 

His potential was especially felt as he was celebrating his 30th birthday on March 16 with a three-hit performance, including a solo home run in an 8-3 victory over the Cincinnati Reds. His consistent performance throughout spring training has provided a boost to the Mariners' lineup, especially significant given the team's limited offseason acquisitions. 

Tellez himself has expressed enthusiasm about joining Seattle, highlighting the supportive environment and the opportunity to contribute to a team with strong pitching and veteran leadership. 

When the Mariners acquired Miles Mastrobuoni from the Chicago Cubs in January, many fans laughed, joking that the veteran was the team's best option at either third or second base. Mastrobuoni is a career .219/.279/.263 hitter across three major league seasons. His spot on this roster was never guaranteed, but that seemed to motivate the 29-year-old utility infielder.

This spring, the former 14th round draft pick hit .429/.488/.571 with more walks (five) than strikeouts (three). His time on the major league roster may be short, but him solidifying a spot on the Opening Day roster wasn't expected by too many people.

Perhaps the biggest surprise of this spring was not an addition, but rather a subtraction that needed to happen. Just a few days ago, the team decided to release veteran outfielder and franchise icon, Mitch Haniger. They will eat his $15.5 million salary for the 2025 season, something that many fans did not expect.

Many expected Haniger to linger into May, possibly even June before the team had the gaul to cut bait with him. Given Haniger's importance to the franchise, this is a tough one to swallow, but for a team that needs to not operate on sentimentalism, but rather in reality, this was the correct decision.

Mariners spring training disappointment headlined by a questionable bullpen decision

In the bullpen, a surprising development is the inclusion of Carlos Vargas over Casey Legumina. Legumina was among the Mariners' top pitchers during spring training throwing 7.1 innings, with a 3.68 ERA and a solid 5/1 strikeout to walk ration, demonstrating exceptional control and effectiveness on the mound. 

Despite Legumina's impressive performance, the decision to retain Vargas appears influenced more by roster management considerations that spring performance, mainly Vargas being out of minor league options. This strategic move suggests that while Vargas has secured a spot for now, his position may be tenuous if he does not perform to expectations early in the season. The Mariners' management is likely to monitor his contributions closely, ready to make adjustments to maintain bullpen strength.​