Rays Reach World Series With Former Mariners Infielder Williamson

Tampa Bay secured a place in the 2026 World Series by defeating the Cleveland Guardians in the American League Championship Series, giving former Seattle Mariners infielder Ben Williamson an opportunity to reach baseball's biggest stage. The advancement marks a significant milestone for the Rays and puts the spotlight on a player Seattle traded away during the offseason.

According to Heavy, Williamson made his major league debut with Seattle in 2025 after the Mariners selected him in the second round of the 2023 MLB Draft out of William & Mary. He appeared in 85 games that season, batting .253 with a .604 OPS, 13 doubles, one home run and five stolen bases. His defensive contributions accounted for much of his 1.2 Wins Above Replacement.

Seattle traded Williamson to Tampa Bay in a three-team deal on February 2, 2026, as the Mariners pursued a roster upgrade involving infielder Brendan Donovan. The transaction also involved the St. Louis Cardinals, who received Jurrangelo Cijntje, Tai Peete and Colton Ledbetter. Seattle's intended addition of Donovan was designed to strengthen its lineup, but injuries limited his availability during the season.

Williamson appeared in 88 regular-season games for Tampa Bay, hitting .238 with a .620 OPS, 10 doubles, one triple and three home runs, according to Heavy. He also stole eight bases in nine attempts. His defensive versatility allowed the Rays to deploy him primarily at second base, while also giving him opportunities at shortstop and third base.

His postseason contributions included one hit in eight at-bats, two walks and two runs, according to Heavy's October 20 report. Williamson also demonstrated his defensive value during Tampa Bay's playoff run, making a notable play at second base in the team's victory over Cleveland.

The move has created an unusual contrast for Seattle, which fell short of reaching the 2025 World Series after losing to the Toronto Blue Jays. Williamson, who did not receive postseason playing time with the Mariners in 2025, now has a chance to compete for a championship with his new team.

However, his progress does not establish that Seattle's trade decision was a mistake. The Mariners sought to improve their roster with Donovan, while Tampa Bay acquired a young infielder capable of contributing defensively and on the basepaths. Williamson's limited power remains a constraint, with three home runs and a .318 slugging percentage in 2026, according to SoDo Mojo.

Former Mariners pitcher Casey Legumina also joined Tampa Bay after Seattle designated him for assignment early in the 2026 season. The 29-year-old recorded a 3.60 ERA across 47 appearances for the Rays, striking out 46 batters in 60 innings, according to Yahoo Sports. However, he was not included on Tampa Bay's American League Championship Series roster and did not appear in a playoff game.

Williamson's World Series opportunity follows a season in which Tampa Bay benefited from his defensive flexibility despite modest offensive numbers. His role in the championship series and potential deployment against left-handed pitching remain relevant considerations as the Rays prepare for the Fall Classic.