Boston Red Sox officials were finalizing a trade to acquire left-handed reliever Erik Miller from the San Francisco Giants at the August 3, 2026, trade deadline, sending infielder Marcelo Mayer to San Francisco in return. The deal remained pending medical review at the time of reporting, a detail tied to Miller’s recent injury history, including a left elbow issue that had sidelined him for stretches of the 2025 and 2026 seasons.
Miller, a 6-foot-5, 269-pound left-hander from St. Louis, has posted a 10-6 record with a 3.05 ERA, 154 strikeouts and four saves across 130 career innings. The reported trade would end his tenure with the Giants and place him in Boston’s bullpen as a controllable left-handed arm still under team control for several seasons.
Trade Details and Medical Review
Reports named the Giants and Red Sox as close to or in agreement on a swap sending Miller to Boston for Mayer, a former first-round pick and one-time top prospect for the Red Sox, according to reports from Ken Rosenthal and Andrew Baggarly of The Athletic. The trade was still contingent on medical clearance, a standard step that carries added weight given Miller’s recent elbow and back injuries. Boston would gain a pre-arbitration-eligible reliever, while San Francisco would receive a young left-handed-hitting infielder.
Injury History Behind the Medical Review
Miller’s medical file explains why the trade required extra scrutiny. He dealt with a lower-back strain in the spring of 2026 that delayed his early-season availability, then returned to the mound and worked effectively for a stretch, including saves against the Milwaukee Brewers and Padres. A left elbow sprain later required a stint on the injured list, and imaging reportedly showed elbow inflammation without structural damage. Teams and medical staff have so far treated the issue with rest rather than surgery.
This is not the first time Miller’s elbow has forced a shutdown. A similar elbow inflammation issue ended his 2025 season early as well, a pattern that adds context to why any acquiring club would want a full medical review before finalizing a deal involving a notable prospect like Mayer.
Path to the Majors
Miller attended De Smet Jesuit High School in Creve Coeur, Missouri, and went undrafted out of high school after committing to Stanford University. At Stanford, he pitched as a starter across three seasons and earned Pac-12 recognition. The Philadelphia Phillies selected him in the fourth round, 120th overall, in the 2019 MLB Draft, and he signed for a $428,300 bonus.
In the Phillies’ system, Miller’s development was slowed by the canceled 2020 minor league season and an injury-shortened 2021, though he showed strikeout ability with a fastball reaching the upper 90s, a slider and a changeup. On January 9, 2023, Philadelphia traded him to the Giants for right-hander Yunior Marte.
Miller thrived after the move, posting a 2.45 ERA with 88 strikeouts and 15 saves in 62 1/3 innings across Double-A Richmond and Triple-A Sacramento in 2023. San Francisco added him to the 40-man roster that November to protect him from the Rule 5 draft.
Giants Tenure
Miller made the Giants’ Opening Day roster in 2024 and debuted on March 28 against the San Diego Padres. As a rookie, he appeared in 73 games, including 10 starts, finishing 4-5 with a 3.88 ERA and 87 strikeouts in 67 1/3 innings.
He opened 2025 strongly, going 4-1 with a 1.50 ERA in 36 appearances before a mild UCL sprain in his left elbow put him on the injured list in early July. He later moved to the 60-day injured list and did not return that season.
2026 Season Performance
Miller returned healthy to open 2026 and settled into a high-leverage bullpen role. Through 38 appearances, he went 2-0 with a 2.76 ERA, 45 strikeouts and four saves in 32 2/3 innings. He briefly missed time in May with a lower-back strain but returned to string together a run of scoreless outings, including consecutive saves in late July against the Brewers and Padres.
Manager Bob Melvin used a closer-by-committee approach for parts of the season, with Miller factoring into high-leverage innings. His performance and left-handed profile made him a trade target as the deadline approached, despite the recurring elbow concerns.
Career Statistics
| Category | Career Total |
|---|---|
| Games | 147 |
| Record | 10-6 |
| ERA | 3.05 |
| Strikeouts | 154 |
| Saves | 4 |
| WHIP | 1.36 |
| Innings pitched | 130 |
Miller has shown the ability to miss bats and limit hard contact when his command is sharp, according to his career pitching profile on Baseball-Reference. His statistical profile, combined with his age and remaining years of team control, made him an appealing target for a Red Sox club looking to add bullpen depth ahead of the deadline.
What Comes Next
The reported trade to Boston remains pending medical review, meaning the deal was not yet finalized at the time of reporting. If completed, Miller would move from a Giants bullpen role into a similar high-leverage assignment in Boston, carrying forward the elbow and back injury history that has interrupted each of his past two seasons. Any final confirmation of the trade would depend on the outcome of that medical evaluation.
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