The Inland Empire 66ers spent most of the year fighting uphill, and the standings show it. They finished with a 59-72 record, good for the second-worst mark in the California League, but the season was never as simple as the win-loss total suggests.
This was the Mariners’ first year with Inland Empire as the organization’s A-ball affiliate, and the roster took a hit from circumstances beyond the club’s control. Because Seattle leaned heavily on college players in the 2025 draft, a lot of the usual low-level contributors skipped this stop altogether and opened the year in Everett instead. Even with that kind of roster churn, the 66ers still produced a long list of notable performers, especially as the season rolled on.
The numbers reflect that split. Inland Empire went 28-38 in the first half with a minus-52 run differential, then improved to 31-34 with a plus-39 run differential after the break.
The offense finished with a .755 OPS, seventh in the league, while the pitching staff carried the group to a 5.04 ERA, second-best in the California League. They also led the league in K/BB ratio at 2.80, a clear sign that the arms were the backbone of this team.
Mason Peters was the biggest breakout on the roster and maybe the biggest riser in the entire Mariners system over the course of the 2026 season. In his first pro campaign, he carved up the Cal League with 50.1 innings, 68 strikeouts, 12 walks and a 1.43 ERA before earning a late-summer promotion to Everett.
Peters doesn’t overpower hitters with velocity, and his frame is on the slight side, but his feel for spinning the ball and his fastball-breaker mix gave him real separation. He’s still behind Ryan Sloan in the organizational pecking order, but he’s making a strong case to be the second-best arm in the system and looks set up for a big 2027 at High-A.
At the plate, Ace Reese came in and looked far too advanced for this level. One of the most impressive performers from the 2026 MLB draft, he hit .440/.530/.667 and posted an OPS that was nearly 1.200.
He probably belonged in High-A or even Double-A, but the dominance was impossible to miss. The only real wrinkle was the defense at third base, where he’s still relatively new and still has plenty of work to do.
Even so, the bat is the selling point, and Reese has made it clear he’s going to hit.
Korbyn Dickerson was another major reason Inland Empire stayed interesting through the grind. The 2025 fifth-round pick handled center field and brought power, speed and impact to the lineup, piling up 35 steals and 15 homers across the year, including 21 steals and nine homers for the 66ers.
His glove in center gives him a premium defensive home, and the offensive tools are loud enough to matter. The bat-to-ball ability still needs polishing, but he started to turn a corner after moving up to Everett.
With several top prospects pushing into the majors, Dickerson could easily climb onto some top-ten Mariners lists this offseason.
Among the sleepers, Hayden Yost stands out as the clearest draft gem so far. The University of Florida outfielder, taken in the fifth round, raked in a small sample and finished with a .999 OPS over 114 plate appearances.
He showed real power, but also enough bat-to-ball skill to make the profile work. His ability to pull the ball in the air and his control of the zone give the production some staying power, and he was a big part of the second-half surge.
A move to Everett next season seems likely.
Jackson Steensma’s season was interrupted by injuries, but there was a stretch when he looked like one of the best pitchers on the staff. He logged 43.1 innings and posted a 4.57 ERA, though his first-half work suggested more upside than that final line shows.
After returning from a multi-month absence in July, his results dipped, but the strikeouts and walk suppression remain encouraging. He’s physical, throws good stuff and has the ingredients of a very interesting arm if health is on his side.
Anderson Guevara is the deep cut, but he’s worth a look for prospect followers who like relievers with bite. His strikeout rate sat just under 38% for the season, and while the command can wander, the slider is a real weapon. It misses bats, and that alone makes him a name to track as a bullpen-type follow in the system.
In Other News...
Randy Arozarena Just Gave Mariners Fans Another Reason To Worry
Randy Arozarena is already giving Mariners fans something to watch this winter, and it has little to do with what he did in Seattle after arriving from Tampa Bay. The outfielder turned in a strong season and has positioned himself as one of the more attractive names in free agency, which is exactly why the Mariners are expected to keep the door open with a qualifying offer even as the larger question around his future starts to take shape.
Arozarena was back in Tampa Bay for the Rays recent pennant-clinching win, and the scene only added to the sense that this could get complicated for Seattle. Former teammate Junior Caminero sent a home run celebration in his direction, a reminder of how much history Arozarena still has there, and why the Mariners may have to brace for the possibility that this stop becomes a brief one. [Read more 🡒]
Mariners Fans Have Every Reason To Fear This Payroll Lesson
Jim Bowdens latest comments land at a familiar pressure point for Mariners fans: the uneasy gap between a club that wants to contend and an ownership group that has long preached restraint. Bowden said some executives around the game are taking the success of small-market teams in October as proof that payroll does not need to keep climbing, a line of thinking that matters in Seattle because the Mariners have tried to thread the needle between developing talent and spending just enough to stay in the mix.
The concern gets sharper with the next Collective Bargaining Agreement looming, since Bowden also said two general managers have weighed lowering payroll depending on where a salary floor lands. John Stanton has made his preference clear in broad terms, favoring investment in younger players over bigger commitments to older stars, and Seattles payroll has stayed relatively flat even with recent increases. For a fan base that has heard plenty about sustainability, the fear is that the lesson being drawn around the league could make it harder, not easier, for the Mariners to push past the middle. [Read more 🡒]
Mariners Old Trade Is Suddenly Stirring Up Value Debate Again
A trade that felt pretty straightforward at the time is getting another look now, because the Mariners December 2018 deal for Edwin Encarnacion has become part of a bigger value conversation again. Seattle got the veteran slugger for salary relief and a short burst of production, but the transaction has generally been remembered as one with limited long-term impact for the club.
What has renewed the interest is the way two of the names involved have resurfaced in the 2026 playoffs. Yandy Daz, one of the players included in that swap, has been a postseason standout, while Jake Bauers has also delivered big October value for another contender. For Mariners fans, it is the kind of old transaction that invites a fresh look at what was given up, what was gained, and how different a deal can look once the postseason spotlight hits. [Read more 🡒]