The Red Sox made a trade searching for upside, but they also departed with one of the team's reliable relief pitchers.

Boston on Saturday traded John Schreiber to the Royals for minor league pitcher David Sandlin. The right-hander was ranked as Kansas City's 20th-best prospect by Baseball America, and chief baseball officer Craig Breslow identified what the Red Sox saw in the 22-year-old.

"Fastball as an amateur was kind of low 90s. In pro ball, it's been up to 98-99," Breslow told reporters, per team-provided video. "Pitches probably at 95-97, good breaking ball and a (change-up) that we see room to optimize. And so it was a combination of raw stuff, projection and a chance to tweak the usage just a little bit and improve performance."

Sandlin commanded a 3.51 ERA in Single-A and High-A ball through 66 2/3 innings last season. Breslow left it up in the air regarding whether or not the right-hander will start out in Salem or Greenville.

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"He's kind of fully ramped up," Breslow said. "We'll get him here, check out what things look like, the progress that he's made this offseason and then make a determination."

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Schreiber turns 30 next month, and he had three solid seasons with the Red Sox with a 2.90 ERA in 114 2/3 innings. He'll join a Royals team that added multiple veterans this offseason, including former Boston pitcher Michael Wacha.

"Really difficult. Like I said, it's not a decision that we made lightly," Breslow said of the trade. "And then when you couple that with what John has been for this team and the personality and teammate that he's been -- I obviously have only gotten to meet him recently -- it's clear the respect teammates have for him and how much he loved his time here. It was tough, but there are certain pockets of the roster where we feel like we've amassed depth, and we need to maintain this balance of short-term and long-term outlooks."

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Breslow believes the bullpen is one of Boston's strengths, and Isaiah Campbell and Greg Weissert will compete for the open spot in the rotation.

Featured image via Eric Canha/USA TODAY Sports Images