New Mariners hitting coach CJ Gillman is more than a much-needed familiar face

The Seattle Mariners don't have a new manager yet, but that apparently doesn't mean they can't hire a new hitting coach. And don't just say "Hello!" to CJ Gillman. Say "Welcome back," too.

According to Ken Rosenthal, Chandler Rome and Spencer Nusbaum of The Athletic, the Mariners have hired Gillman to fill Kevin Seitzer's vacated chair as the club's lead hitting coach. He's coming to them after a year with the Washington Nationals as their director of hitting. Before that, Gillman was Seattle's minor league hitting coordinator from 2022 to 2025.

[As a side note, Gillman also helped recruit Paul Skenes to the Air Force Academy.]

You can do the math from Gillman's previous time with the Mariners and see the appeal. He was the guy overseeing the minor league bats as Cole Young, Colt Emerson, Lazaro Montes and Michael Arroyo were coming up through the system. All four could be everyday players in 2027, so who better to unlock their full potential than the guy who helped chart their potential in the first place?

This is not to downplay the tall order that lies before Gillman in 2027. He's inheriting an offense whose awfulness contained multitudes this year, resulting in the fourth-lowest OPS and third-lowest rate of runs per game of any team in the league.

In addition to unlocking the young guys, Gillman will have to get more out of Cal Raleigh, Julio Rodríguez and Josh Naylor. In fact, with Randy Arozarena gone, the only incumbent Mariner who doesn't need to be more productive in 2027 is Dominic Canzone.

CJ Gillman's work with the Nationals offers a window into his Mariners upside

Then again, the Mariners don't merely know what Gillman is capable of from his previous time in the organization. They also have eyes, and can therefore see just how big of an impact he made for Washington in just one season.

He primarily worked with their minor leaguers, who made huge year-over-year jumps with their productivity. He also had influence with the Nationals' major league offense, which went from 20th in MLB in scoring in 2025 to third in MLB in scoring this year.

Here are some changes to key performance indicators that stand out:

• BB%: +1.6% (T-1st in MLB)
• K%: -0.8% (10th in MLB)
• Launch Angle: +3.7% (1st in MLB)
• Barrel%: +0.9% (2nd in MLB)

Gillman's mantra is “crush strikes in the air.” You can really see it in these figures, which hint at a better quality of at-bats and power-efficient swings. Though it was the quality of the at-bats that primarily drove fans crazy in 2026, the Mariners could stand to do better on both of those same fronts in 2027.

A major difference between Seattle and Washington is that the Nationals play in a hitter-friendly park, while the Mariners most definitely do not. But even to this extent, Gillman at least knows what he's getting into. And as much as we'd like to see a more holistic style of offense, patience + power is the closest thing to a fool-proof philosophy for T-Mobile Park.

All we need to know now is who Gillman will be reporting to. Barring any surprises, it'll be either Joe Espada or Jason Kanzler in the manager's chair. Since they both come from player development backgrounds, one can't help but wonder if the Gillman hire is a prelude to a Kanzler hire.

We'll find out soon enough.

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