The Athletic has live coverage of the 2026 MLB Trade Deadline.In an effort to bolster their pitching staff, the Boston Red Sox are trading former No. 4 overall pick Marcelo Mayer to the San Francisco Giants for left-hander Erik Miller. League sources told The Athletic. The sources spoke under condition of anonymity to discuss a deal that had not been completed.Mayer, who is currently on the IL with a bone stress reaction, has not played since June 25. His timeline for a return has not materialized.In Miller, 28, Boston is receiving a controllable southpaw with above-average velocity and elite suppression of hard contact. He pairs a fastball that touches 99 mph with a wipeout slider that misses bats at an elite level. He was one of the game’s top lefties two years ago after the Giants got him for practically nothing from the Phillies.There was a reason he was so available, though, as he battled an assortment of injuries along with command issues. Miller dealt with more elbow soreness last season, and although he’s stayed healthier this year, a high walk rate (6.1 per 9 innings) has prevented him from repeating every aspect of his success in 2024. Miller will be eligible for arbitration next year and won’t be a free agent until 2030.