Mariners add Michael Rucker from Tacoma, DFA Domingo González as Seattle reshapes the bullpen

The Seattle Mariners made another adjustment to their pitching mix on Tuesday, selecting right-hander Michael Rucker from Triple-A Tacoma and designating Domingo González for assignment one day after bringing him back to the big leagues. The move underscores how Seattle is trying to stabilize leverage innings while managing the constant churn that comes with a short-handed bullpen and an active late-season roster.

Rucker, 32, is the latest local flavor in the organization’s rotation of arms. He starred at Auburn Riverside High School (class of 2012) before heading to college, first pitching at Gonzaga University and then transferring to Brigham Young University. After college, he was selected by the Chicago Cubs in the 11th round of the 2016 draft, making his major-league debut with Chicago in 2021.

His path to Seattle has been defined by opportunity and role flexibility. According to Yahoo Sports, Rucker has worked largely in relief and has appeared in 96 major-league games across 123 innings, compiling a 4.96 ERA and a 4.51 FIP during that span. The same report notes that injuries disrupted his 2025 season, but that he has pitched with more rhythm in the minors since.

This season’s numbers in Triple-A have been the clearest reason for the timing of the promotion. Yahoo Sports reported that Rucker has posted a 1.93 ERA and 3.95 FIP across 22 games for Tacoma. Even so, the Mariners are not calling him up to be a long-term solution in the deep bullpen. The immediate expectation, as framed in the report, is that he will help cover innings in the next day or two, potentially filling a gap created by Seattle’s recent recall-and-designation sequence.

The corresponding roster move involved González, who had been recalled and then quickly designated for assignment. In MLB terms, DFA triggers a limited window for the team to trade the player, release him, or place him on waivers, where other clubs can claim him and assume the contract. The speed of the sequence suggests Seattle is responding to short-term performance needs and roster availability, rather than making a gradual change.

For Rucker, the promotion represents another late-career reset. He is not arriving as a top prospect, but his pitching background and recent Triple-A production give the Mariners a reason to test whether his current form can translate to the majors. The next watch for Seattle will be how quickly the bullpen settles around him, particularly whether he is used in middle innings, higher-leverage matchups, or as a multi-inning bridge.

If González clears waivers or is traded, Seattle’s bullpen options could shift again, potentially altering the role assignments for other relievers. For fans, the storyline is less about one move and more about the Mariners’ ongoing effort to find the right mix of innings-eaters, matchup specialists, and swing men as the roster continues to change night to night.