Red Sox expected to designate Seth Martinez for assignment, recalling lefty Alec Gamboa

The Red Sox are expected to make a 40-man roster change that underscores how quickly bullpen usage can ripple into personnel decisions late in the season. According to Chris Cotillo of and as summarized by MLB Trade Rumors, Boston plans to designate right-hander Seth Martinez for assignment, which would remove him from the active 40-man group and expose him to waivers.

In the same transaction framework, the Red Sox are expected to replace Martinez’s roster spot with a recall. MLB Trade Rumors reports that left-hander Alec Gamboa is being brought back after time at Triple-A Worcester, a move attributed to Tommy Cassell of the Worcester Telegram & Gazette. The timing suggests Boston is trying to match roster availability with the needs of the pitching staff as the stretch run approaches.

For Martinez, being designated for assignment is often a reset point. After a player is designated, the team has a limited window to trade him, release him, or put him through the waiver process, after which the player’s immediate destination depends on claims. The practical outcome is that his stay in Boston’s current bullpen mix was likely shorter than planned, at least for the moment.

Gamboa’s recall changes the picture in a different direction. By moving a left-hander into the role of roster addition, Boston can alter the matchup options available to its bullpen. Left-right bullpen balance is a standard lever managers use to handle late-inning matchups, and the recall indicates the Red Sox are actively managing that flexibility.

The fact that this is being described as “expected” is important. MLB Trade Rumors frames the move as forthcoming, meaning the final roster actions could differ if Boston reverses course, if another transaction intervenes, or if the club decides to pursue an alternative to a designation. Until an official transaction is posted by the Red Sox, the most accurate view is that Boston is trending toward this specific roster path rather than announcing it as complete.

From a broader team-building standpoint, the maneuver also reflects a common late-season reality in MLB: roster spots are never static, even for players the club recently had on the 40-man. With the active season pace and the need to keep multiple arms available, teams often rotate pitchers in and out to cover innings, respond to performance changes, and adjust to upcoming series demands.

What to watch next is straightforward. If Boston designates Martinez, the next headline will be whether he is claimed on waivers or remains within Boston’s organization through waivers clearing. Separately, Gamboa’s first appearance back on the roster, and how the Red Sox deploy him within games, will show whether he’s being used as a specific matchup piece, a multi-inning option, or depth protection for the bullpen rotation.