Mariners moving on from Single-A Modesto, to play in Inland Empire in 2026

SEATTLE -- The Mariners on Thursday announced the sale of their Single-A affiliate, the Modesto Nuts, to Diamond Baseball Holdings, terms of which were not released.

The club will remain in Modesto as the Nuts in 2025 before moving to San Bernardino, Calif., to play as the Inland Empire 66ers in 2026, which was a DBH decision. The Mariners, who’ve been in Modesto since 2017, had two previous affiliations in San Bernardino, from 1987-1994 and 2001-2006.

“When we purchased the Nuts, our goal was to guarantee a spot in the Cal League,” the Mariners said in a press release. “That was important to us for competitive reasons in developing our players to assist us in winning at the big league level.”

The Mariners had been in negotiations with the City of Modesto regarding upgrades to John Thurman Field but could not reach an agreement on financial terms for improvements to the facility, The Modesto Bee reported in July. The ballpark there was originally built in 1955 and renovated in ‘97.

DBH, which was formed in 2021 in partnership with MLB as part of the league’s grander restructuring of the Minors, owns 41 Minor League teams, including the Mariners’ Double-A affiliate, Arkansas.

“Following the changes in the Minor League system in recent years, it is no longer necessary for us to own a team to be confident in our ability to remain in the Cal League, so we are transferring the team to DBH,” the Mariners said.

“Diamond has built their business model around owning Minor League teams, while our baseball operations focus is on assuring the best on-field development of our young players. Exiting as owners of the Nuts allows both the Mariners and Diamond to focus on their strengths.”

The 66ers play in the California League and play at San Bernardino Stadium. The Cal League plays at the Single-A classification, just below the High-A Northwest League, where the Mariners’ affiliate is the Everett (Wash.) AquaSox.