DENVER -- The Rockies' search for left-handed relief gems landed them Yoan Aybar, acquired Thursday from the Red Sox in exchange for Minor League infielder and 2019 12th-round Draft pick Christian Koss.

Aybar, 23, spent four seasons in the Red Sox’s system as an outfielder before converting to the mound in 2018. In 61 career relief appearances across four levels, the highest being Class A Advanced, Aybar is 3-4 with a 4.45 ERA alongside 97 strikeouts and 55 walks in 85 innings pitched.

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After a 2019 Arizona Fall League with some mixed stats (0-1, 6.75 ERA, nine strikeouts and six walks in eight innings pitched), the Red Sox saw enough in Aybar to place him on their 40-man Major League roster following the '19 season. Aybar joins the Rockies’ Major League roster, which is two below the limit.

In 2019, Aybar’s fastball ranged “93-98 mph, average 96, with an above- to well-above average slider,” and is 6-foot-2, 210 pounds with solid athletic tools, according to Jon Weil, the Rockies' assistant general manager, player personnel.

“Jack Gillis is the scout that has seen him over the years since 2015,” Weil said. “For Aybar, it’s just a matter of getting more consistent on the mound and throwing more consistent strikes. But we like the athlete, we like the body and really like the projection for the stuff to play at the Major League level from an impactful standpoint.”

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This offseason, after the Rockies finished 2020 with no left-handers in the bullpen, they have accumulated depth pieces. They have signed to Minor League contracts Brian Gonzalez, formerly in the Orioles' system, and Ian Clarkin, formerly in the Cubs' system. On the 40-man Major League roster are Phillip Diehl, who showed promise in 2019 but was scored upon in four of his six '20 outings; and Ben Bowden, a second-round Draft pick in '16 who has seen injuries keep him out of the Majors.

The Rockies are expected to seek low-cost options with Major League experience, as well, but could not pass up Aybar’s arm potential.

Although the COVID-19-affected season took away the Rockies' ticket revenue and hurt in ways that are already affecting the ability to hold onto their Major League roster, the Rockies did not lay off any of their full-time employees, including those who shape the on-field product. The hope is that maintaining their scouting department can be an edge finding unheralded players like Aybar who can help, whether in 2021 or beyond.

Red Sox-bound Koss, 22, from the University of California, Irvine, batted .332 with 11 home runs, 11 doubles and four triples at Rookie-level Grand Junction in 2019.

"We’re always looking for ways to upgrade our depth with as many impact-type tool guys that we can,” Weil said. “Especially if you can get an arm like this -- trading a player who we like, but getting a guy that fills a void for us in our system, in our prospect depth.”