(Story has been updated at 2:52 p.m. PT and 4:37 p.m. PT to reflect updated trade packages)

On Day 1 of FanFest at T-Mobile Park in Seattle, Seattle Mariners president of baseball operations Jerry Dipoto said he felt like the team had "one more move" in them and the front office has been "grinding hard" to make it happen.

On Monday, it happened.

After almost an entire offseason's worth of reports, rumors and speculation, the Seattle Mariners acquired All-Star second baseman/outfielder Brendan Donovan from the St. Louis Cardinals in a three-team trade involving the Tampa Bay Rays, according to ESPN MLB insider Jeff Passan.

The total return for all three teams wasn't revealed at the time of the report (1:27 p.m. PT) but it was reported by USA Today's Bob Nightengale that the Rays received third baseman Ben Williamson from the Mariners.

According to a report from Ryan Divish and Adam Jude of the Seattle Times, the packages have been finalized but the three clubs are still waiting to receive medicals and to notify players.

According to a report on "X" at 2:47 p.m. PT from Jude, the M's sent outfield prospect Tai Peete and switch-pitching prospect Jurrangelo Cijntje to St. Louis in addition to dealing Williamson to Tampa Bay.

Passan also reported that the M's would also be sending a Competitive Balance Round B MLB Draft pick to St. Louis

Donovan has been tied to Seattle in rumors for the entire offseason. The team was rumored to have interest in the one-time Gold Glover dating back to the winter of 2024-25. He'll earn $5.8 million in his second year of arbitration in 2026.

Donovan, who has two more years of team control on his contract, slashed .282/.361/.411 with a .772 OPS in four seasons with the Cardinals. He hit 97 doubles, five triples and 40 home runs with 202 RBIs.

The 29-year-old, who made his first All-Star game last year, slashed .287/.353/.422 with a .775 OPS and hit 32 doubles and 10 homers with 50 RBIs.

With the understanding that the trade packages still aren't public, Donovan play second base for the Mariners in 2026. The projected lineup for 2026 is projected to look as something similar to the following:

Cal Raleigh, C
Josh Naylor, 1B
Donovan/Cole Young, 2B
Colt Emerson/Miles Mastrobuoni/Donovan, 3B
J.P. Crawford, SS
Randy Arozarena, LF
Julio Rodriguez, CF
Victor Robles/Dominic Canzone, RF
Canzone/Rob Refsnyder/Luke Raley, DH

Seattle was one of the best power-hitting teams in baseball last season. It ranked third in the major leagues and second in the American League in homers in 2025 (238). Second baseman Jorge Polanco (New York Mets) and third baseman Eugenio Suarez (Cincinnati Reds) both signed elsewhere this offseason.

Between those departures and the unlikelihood Raleigh will be able to replicate his historic 60-homer season, the Mariners will likelihood go with a more average and on-base-heavy approach in '26, which Donovan fits.

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