Red Sox Sign Brad Keller

11:50AM: The Red Sox have officially announced Keller’s signing and optioned Kelly in the corresponding move.

10:12AM: The Red Sox are nearing a deal with right-hander Brad Keller, according to MassLive’s Chris Cotillo. The deal is pending a physical and the club hopes to make it official before today’s game against the Brewers, which is scheduled to begin at 1:35pm local time. Cotillo adds that right-hander Zack Kelly has been optioned to the minors to make room for Keller on the active roster. Boston’s 40-man roster currently stands at 39, so no corresponding 40-man move will be necessary to add Keller.

Keller, 28, signed with the White Sox on a minor league deal back in March and made five appearances with the club, including two starts, before being designated for assignment last week. Keller subsequently elected free agency and returned to the open market with a 4.86 ERA in 16 2/3 innings of work with Chicago under his belt. That performance may be better than what Keller earned, as he struck out just 17.1% of batters faced while walking 7.9% and allowing a whopping 29.4% of his fly balls to leave the yard for home runs. Those iffy peripherals left him with a 6.55 FIP and a 5.16 xERA, although a 4.02 SIERA and 4.09 xFIP both suggest Keller’s ERA was actually higher than what should have been expected based on his underlying performance.

Regardless of the results from Keller’s time with the White Sox, he’ll now get another opportunity to re-establish himself at the big league level in Boston. Keller was once a promising mid-rotation arm with the Royals, as he posted a 3.50 ERA and 3.90 FIP across his first 360 1/3 innings of work in the majors between 2018 and 2020. Since then, however, his results have declined drastically. His final three seasons in Kansas City saw him post a 5.14 ERA with a 4.79 FIP before he was ultimately sidelined partway through the 2023 campaign by a shoulder issue before undergoing surgery to correct Thoracic Outlet Syndrome back in October. TOS is a particularly difficult injury for players to come back from, and players such as Stephen Strasburg and Chris Archer have seen their careers negatively impacted by the issue in recent years.

Keller will hope to buck that trend with the Red Sox, joining a pitching staff that appears poised to lose right-hander Garrett Whitlock to elbow surgery after already losing righty Lucas Giolito to that same procedure earlier in the year. The club is currently relying on a starting rotation of Brayan Bello, Tanner Houck, Kutter Crawford, Cooper Criswell, and Nick Pivetta. While it’s possible that Keller could slot somewhere into that mix, a more likely scenario would be Keller joining veteran righty Chase Anderson as a potential multi-inning relief and spot starter option in the club’s bullpen mix.

Making way for Keller on the club’s active roster is Kelly, who is in his third season as an up-and-down reliever for the Red Sox. The right-hander has generally pitched to solid results when in the majors for the club, with a career 3.18 ERA across 39 2/3 innings of work. Kelly has been particularly effective this season, with a strong 2.16 ERA in 16 2/3 frames despite a 19.4% strikeout rate and a massive 13.9% walk rate that have left him with a lackluster 4.99 FIP. Now back in the minors, Kelly figures to act as optionable depth for the club going forward alongside Josh Winckowski and Naoyuki Uwasawa.