The Colorado Rockies bolstered their bullpen on Monday by activating the recently acquired Mychal Givens, as well as recalling prospect Antonio Santos, according to a club announcement.

Santos’ first appearance, whenever that might be, will be his major league debut. The 23-year-old right-hander, who hasn’t pitched above Double-A, has made just one regular season relief appearance during his minor league career, which began in 2015 in the Dominican Summer League. In parts of five seasons as a starter, Santos posted a 4.57 ERA in more than 500 innings spanning 100 starts, maintaining a strong walk rate of just 1.7 per nine innings with average strikeout numbers.

The Rockies, perhaps sensing Santos would be a better fit as a reliever, sent him to the Arizona Fall League in 2019 to make some appearances out of the bullpen. The experiment was a success; Santos posted a 2.77 ERA in 13 innings across eight appearances, striking out 16 batters while issuing only two walks.

Santos will likely sit at around 94-95 with his fastball out of the bullpen, with the ability to mix in some 97s. None of his secondary pitches—slider, curveball, and changeup—rate as particularly great, although he’s shown the ability to throw all of them for strikes. But a big reason the Rockies decided to try him out as a reliever has to do with their belief that at least one of those pitches can be an effective offering in short stints.

The additions of Santos and Givens should give the Rockies’ bullpen a shot in the arm, though the bar for success isn’t exactly being set too high; Colorado relievers have allowed 17 runs in 13 2/3 innings of work during their current four-game series agains the San Diego Padres. James Pazos, whom Santos will be replacing, was optioned to the Rockies’ alternate training site after posting a 16.88 ERA in six appearances. With that move, Colorado now has just one left-handed reliever—Phillip Diehl—in its bullpen.