The Seattle Mariners and the Modesto Nuts have made a significant announcement today. The Mariners' Low-A affiliate has been sold to Diamond Baseball Holdings. Alongside this, it was revealed that 2025 will be the final season for the Nuts in Modesto. The reigning California League champions are set to move to San Bernardino, CA, and will functionally become the Inland Empire 66ers, although there are expected changes to the branding.

Impact on the California League and Minor League Baseball

This move is part of a series of changes across the California League and is a result of MLB's consolidation of control over Minor League Baseball in recent years. The Mariners' Low-A affiliate will remain in the California League, which the club considers a core priority. By moving the Nuts to San Bernardino, Seattle will once again have an affiliate at Inland Empire, where the organization began after a move from another California town.The Salinas Spurs became the San Bernardino Spirit in 1987 and were the Mariners' affiliates until 1994. After a half-decade with the Los Angeles Dodgers, the then-Stampede returned to the Mariners from 2001 to 2006. During this time, their title changed from the San Bernardino Stampede to the Inland Empire 66ers of San Bernardino. This multilocational title presaged their more recent affiliation, as they have been the Single-A club for the Los Angeles Angels of Anaheim since 2011 after another few years with the Dodgers.The current Inland Empire club will be moving to Rancho Cucamonga, CA, similar to the founding of the Rancho Cucamonga Quakes in 1987. The current Inland Empire organization will technically move to Rancho Cucamonga while remaining the Angels affiliate. Meanwhile, the Quakes will move to Ontario, CA, and retain their Dodgers affiliation. The city of Ontario is in the process of constructing a $100 million sports complex centered around the new stadium for the Dodgers' new affiliate.

Modesto's Heartbreaking Departure

Modesto is left as the odd city out, which is a heartbreaking outcome for a city with over 200,000 residents. The city has seen continuous play since 1946 and has been affiliated with MLB since 1948. It has been the home to six future Hall of Famers as players and was one of the first stops for Sparky Anderson on his path to the Hall as a manager. The Nuts have been the first stateside stop for many of the Mariners' international players and the first taste of pro ball for many draftees. This is the second time in the past half-decade that Seattle's departure (as part of MLB's broader shrinking of affiliated minor league baseball) has left their Single-A affiliate without a home, similar to the West Virginia Power's situation in 2021. Now the Charleston Dirty Birds, the organization is part of the independent Atlantic League. The Pioneer League and Pecos League are two larger independent league organizations operating in the American West and could potentially offer high-level baseball at John Thurman Field.

Developmental Impact and Park Factors

In terms of pure developmental impact, Modesto's park is generally the most difficult for hitters in the California League. Its high walls make it more challenging for sluggers, not only yielding the most difficult home run environment in the Cal League but also in all of Low-A. Contrary to the California League's generally hitter-friendly reputation, this has had an impact. The curvature of the walls and their height do induce a significant number of triples. Inland Empire, on the other hand, is a more extreme triple-friendly environment but also offers a more measured offensive environment according to Baseball America's minor league park factors. While San Manuel Stadium grades as around 16 percent more homer-conducive over the past few seasons, it is still well below the homer-happy rest of the league. Essentially, when the 2026 Low-A numbers start to come in, it's important to remember that Seattle's prospects will be playing in more favorable or tougher locales for hitting or pitching on a regular basis.