Three questions facing the Seattle Mariners this offseason

The Seattle Mariners came agonizingly close to their first World Series appearance.

The Mariners had won three of the first five games in the ALCS and held a 3-1 lead heading into the bottom of the seventh inning in Game Seven. Blue Jays outfielder George Springer belted a three-run home run, ending those World Series dreams.

The Mariners have several key roster pieces set to enter free agency, including third baseman Eugenio Suarez and first baseman Josh Naylor. Seattle may have won the AL West and game within a game of the World Series; the hardest part may be returning to the ALCS in 2026.

Three questions for the Seattle Mariners heading into the offseason

1. Can the Mariners keep Josh Naylor?

While Suarez was a key power bat in the middle of the Mariners' lineup, he will turn 35 years old during the 2026 season. He will also command a significant contract in free agency, something that the Mariners may not want to pay. Instead, the Mariners' focus is on their other trade deadline acquisition.

Naylor was one of the Mariners' best players over the final two months of the season, posting a .299/.341.490 batting line with nine homers and 10 doubles over 210 plate appearances while stealing 19 bases. He is reportedly the Mariners' top free-agent priority, as he proved to be a perfect fit in the lineup. Naylor may be expensive in his first time in free agency, but he would be well worth the cost.

2. How much will the Mariners spend in free agency?

Payroll has been a concern for the Mariners over the past two offseasons, limiting their activity in free agency. Suarez was traded to the Diamondbacks during the 2023-24 offseason to clear his salary from their ledger. 

This offseason promised to be different. The Mariners reportedly have more payroll flexibility in the wake of their playoff push, potentially allowing them to retain Naylor and add other pieces. Seattle also has one of the best farm systems in baseball, giving president of baseball operations Jerry Dipoto and GM Justin Hollander plenty of ammunition on the trade front. The Mariners may also be able to take on a contract or two, opening another avenue as they look to improve the roster.

3. Will pitcher Luis Castillo be traded this offseason?

Trade rumors have swirled around Castillo despite his no-trade clause. That clause expires this offseason. Castillo, who posted a solid 3.54 ERA and a 1.185 WHiP over 180.2 innings, striking out 162 batters with 46 walks, would be one of the best pitchers available if he were put on the trade block.

There are risks to such a move. Castillo and Bryan Woo were the only Mariners pitchers to make at least 30 starts in 2025; Woo battled injuries during the postseason and was not himself during the ALCS. Logan Gilbert, Bryce Miller and George Kirby all missed time with injuries. Castillo's velocity and effectiveness may be declining, but he has also made at least 30 starts and thrown at least 175 innings in each of the last three years. Trading Castillo could make the Mariners better in the future, but such a move would be a considerable gamble for the 2026 season.