Mikolas, who made 37 appearances over three seasons with the Padres and Rangers from 2012-2014, spent the last three seasons with the Yomiuri Giants in Japan. He posted a 2.18 ERA in 62 starts over that span, a stellar performance that led to his interest to come back to the majors after the season.
Mikolas most recently logged 188 innings of 2.25 ERA ball for Yomiuri last season and will likely be viewed as a rotation candidate for St. Louis. The Cards were slated to have a rotation that included Michael Wacha, Jack Flaherty, Luke Weaver and the rehabbing Alex Reyes behind veterans Adam Wainwright and Carlos Martinez, so the addition of Mikolas gives them added flexibility if they wanted to trade one of those young arms for a bat. St. Louis remains one of two teams in the running for Marlins slugger Giancarlo Stanton and has been rumored to be willing to include young arms in their proposed package for him.