Mariners officially hire C.J. Gillman, Tanner Swanson as coaching staff takes shape

LAS VEGAS — With the MLB general managers meetings starting on Monday at the Aria Resort & Casino, the Mariners’ front office, along with new manager Jason Kanzler, are working to finalize the remainder of their MLB coaching staff.

The team officially announced the hirings of Tanner Swanson as bench coach and C.J. Gillman as hitting coach on Monday afternoon. The hiring of both coaches had already been confirmed and reported leading up to the announcement.

“I am excited to have Tanner and CJ join our coaching staff,” Kanzler said in a statement. “Both individuals bring an exceptional understanding of the game and skillsets that I am confident will help maximize the talent on our roster.”

Swanson, 44, has spent the last six seasons as a coach on Yankees big league staff, holding various duties, including catching coordinator, quality control and field coordinator.

Swanson was born in Seattle, but grew up in Roslyn and attended Cle Elum-Roslyn High School. He played at the junior college level for Green River and Everett before transferring to Central Washington University where graduated with a degree in physical education and school health, while playing baseball and earning an academic all-conference selection for the Wildcats.

After a brief stint as a teacher and coach at Sultan Senior High School, he started a college coaching a career at Everett Community Colege and later five seasons with the University of Washington (2013-2017). He got his start in progressional baseball as the minor league catching coordinator for the Twins from 2018-19.

Swanson is considered one of the top catching coaches in baseball at all levels, having established founded a private coaching firm called “D1 Catching” during his college coaching days. It was the first specialized program designed to train catchers, particularly on the art of pitch framing. While with the Twins, Swanson helped bring the one-knee-down catching technique, which is now the standard in the sport.

Gillman, 37, returns to the Mariners after spending last season as the director of hitting for the Washington Nationals.

The Mariners finalized the details for hiring Gillman while they were interviewing Kanzler and Joe Espada for the manager job.

“I was definitely in the loop,” Kanzler said at his introductory press conference. “I think I told Justin over breakfast, ‘whoever the manager is, I think C.J. Gillman needs to be the hitting coach here.”

Kanzler tried to hire Gillman as a minor league hitting coordinator while he was overseeing the Cubs farm system.

“I think he’s great.,” Kanzler said. “I think things he does are great. I think what he stands for is excellent. His content is excellent. His methods of communicating and coaching are outstanding. So he’s been on my list for a while as just like excellent, excellent director, hitting coach target. We’ve been communicating a lot the last few days.”

Prior to that, he had served as the Mariners’ director of minor league hitting from 2022 to 2025, building strong relationships with several of Seattle’s top prospects — Cole Young, Colt Emerson, Laz Montes and Michael Arroyo — who will all likely be on the MLB opening day roster. He also supplemented the MLB team’s coaching staff throughout his tenure, including after hitting coach Jarret DeHart was fired late in the 2024 season.

Gillman was a part of Nationals’ coaching staff that helped create one of the best offense in MLB. The Nats finished third in MLB with 821 runs scored, a significant increase from the 687 runs scored in 2025. The Mariners scored 664 runs as a team in 2026.

A graduate of the University of Dayton where he was an all-conference player, Gillman played two seasons in the independent Frontier League before starting his coaching career at his alma mater. He then served as an the recruiting coordinator/assistant coach for the United States Air Force Academy before joining the Reds as a minor league hitting coordinator (2020-2021).

The Mariners are in the process of adding at least three coaches to the staff. They still must fill the first base coach spot previously held by Eric Young Jr. They are also going to add at least one, if not two, assistant hitting coaches to help Gillman. They could also add another coach to assist in either outfield or infield defense.

The Mariners current staff under Kanzler is currently:

• Tanner Swanson — bench coach
• Edgar Martinez — senior director of hitting strategy
• C.J. Gillman — hitting coach
• Trent Blank — director pitching of strategy/major league coach
• Pete Woodworth — pitching coach
• Danny Farquhar — assistant pitching coach and pitching strategist
• Austin Nola — bullpen coach
• Carlos Cardoza — third base coach
• Jake McKinley — major league field coordinator