Santillan underwent ankle surgery during the offseason but has been throwing bullpens to begin spring training, Bobby Nightengale of The Cincinnati Enquirer reports.
Santillan made his major-league debut in 2021 and recorded a 2.91 ERA and 1.27 WHIP in 43.1 innings across 26 appearances (four starts). General manager Nick Krall classified Santillan's surgery as a right ankle debridement that he underwent on Oct. 29, Charlie Goldsmith of The Cincinnati Enquirer reports. It's not yet clear whether the right-hander's offseason procedure will force him to miss time early in the regular season, but the fact that he's already throwing bullpens signals that any potential absence is unlikely to be a significant one.