MIAMI — The San Francisco Giants have shifted right-hander Adrian Houser from the starting rotation to the bullpen ahead of Tyler Mahle’s scheduled return to the mound, creating a crowded pitching staff and prompting difficult decisions for the team.

Manager Tony Vitello informed Houser of the change on Saturday, a move the 33-year-old veteran opposed but ultimately accepted. “I signed here to be a starter. I didn’t sign here to be in the bullpen,” Houser said, acknowledging his dissatisfaction but expressing understanding of the team’s position.

Houser’s performance has fallen short of expectations during his first three months with the Giants. In 14 starts, he recorded a 2-6 win-loss record with a 5.73 ERA and a 1.573 WHIP—marks representing the highest of his career and ranking among the poorest for starters with comparable innings pitched. Left-handed hitters have proven particularly challenging, accounting for nine of the 12 home runs he surrendered and posting a .339 batting average against him, while righties hit .218. His struggles have been most pronounced in the first inning, where his ERA stands at 9.64, and in the fifth inning, with an even higher 12.46 ERA, though his middle innings tell a different story, with a much improved 2.79 ERA.

Vitello noted that Houser has shown the ability to find rhythm during outings but has had difficulty with the first inning and facing batters the third time through the order—areas in which he previously had success. These performance issues contrast with Houser’s track record, highlighted by a 3.31 ERA over 21 starts last season between the Rays and White Sox, which factored into Giants president Buster Posey’s decision to sign him to a two-year, $22 million contract this offseason.

Mahle, meanwhile, has struggled as well in the rotation, posting a 1-7 record with a 6.04 ERA over 11 starts. Unlike Houser, Mahle is under contract only through the current season, carrying a $10 million salary. The Giants have suggested he could be a candidate for trade at the July deadline. Mahle’s recent stint rehabbing with Triple-A Sacramento did not immediately alleviate concerns, as he allowed five walks in three innings. Despite these issues, Mahle is slated to start against the Oakland Athletics on Wednesday, with Vitello aiming to incrementally increase Mahle’s pitching workload through bullpen sessions.

With Mahle’s return imminent, the Giants have needed to resolve the impending surplus of starting pitchers. Houser will now serve out of the bullpen, a role he has historically expressed reluctance toward. The team is considering adjustments to Houser’s approach to address his struggles against left-handed batters, emphasizing pitch selection and sequencing. Pitching coach Justin Meccage pointed to the need for a more varied mix, including increased use of a four-seam fastball and strategic pitch placement to disrupt hitter timing.

One potential solution discussed internally is the use of a left-handed opener to precede Houser, aiming to mitigate his early-inning difficulties against left-handed hitters. However, Houser has not been formally approached about this strategy and indicated he would prefer to maintain his routine rather than adopt such changes.

Houser’s reassignment to the bullpen marks a significant shift for the pitcher, who had started 139 of his 187 career major-league appearances. He remains committed to working toward a return to the starting rotation, emphasizing the importance of striking out batters and earning the trust of the Giants’ coaching staff.

Vitello acknowledged the challenges in delivering such news to a player of Houser’s stature and experience but emphasized the necessity of balancing roster needs. As the Giants prepare for Mahle’s comeback, Houser’s role and future contributions remain a key focus for the team’s pitching staff moving forward.