How Red Sox Unintentionally Helped Cubs Land Breakout Star

Jun 26, 2017; Washington, DC, USA; The cap and glove of Chicago Cubs second baseman Javier Baez (9) rest in the dugout against the Washington Nationals at Nationals Park. Mandatory Credit: Geoff Burke-Imagn Images | Geoff Burke-Imagn Images

The Boston Red Sox's pitching development machine has received a lot of acclaim over the past two seasons, but one of its success stories is now unfolding outside the organization.

Last May, the Red Sox signed right-handed Brad Keller just after he was designated for assignment by the Chicago White Sox, the team that would finish with the worst record in baseball history. From a birds-eye view, it appeared to be a throwaway transaction, as Keller went on to pitch to a brutal 5.84 ERA in 11 big-league outings for the Red Sox before electing free agency in November.

However, after signing a minor-league deal with the Chicago Cubs in January, Keller has unexpectedly popped off. The 30-year-old owns a sparkling 2.13 ERA in 67 2/3 innings and looks to be one of the most reliable pieces of the Cubs' bullpen heading into the postseason.

Brad Keller's work with Red Sox keying success with Cubs

Sep 15, 2025; Pittsburgh, Pennsylvania, USA; Chicago Cubs relief pitcher Brad Keller (40) pitches against the Pittsburgh Pirates during the ninth inning at PNC Park. Mandatory Credit: Charles LeClaire-Imagn Images | Charles LeClaire-Imagn Images

On Monday, Patrick Mooney of The Athletic wrote a profile on Keller that revealed his time in the Red Sox organization helped unlock the improvements the right-hander has seen in Chicago, though Boston never got to see that work pay off for themselves.

"The Boston Red Sox quickly added Keller, exposing him to new information and different ideas about pitching while he bounced between the majors and Triple A," Mooney wrote.

"Keller’s experience with the Red Sox, combined with his offseason program at the Maven Baseball Lab in Atlanta, helped clean up his mechanics and boost his velocity. A groundball pitcher suddenly had more swing-and-miss stuff."

The Red Sox have been searching all season for righties to back up Garrett Whitlock in high-leverage situations, so seeing Keller perfectly fill that role for another team is particuarly painful. Plus, just as a little extra salt in Red Sox fans' wounds, Keller threw perfect innings in both of the Cubs' wins over Boston in July, striking out the side in the second game.

“I feel like I’ve grown a lot as a pitcher,” Keller said, per Mooney. “I feel like I’ve added a lot to my arsenal and things like that. My mentality on the mound has changed quite a bit."

Hopefully, for the Red Sox's sake, baseball karma allows Boston to capitalize on the improvements a player made in another organization sometime soon.

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