Thomas was added to the Cardinals' 40-man roster Tuesday.
The 24-year-old southpaw lacks upside (17.9 percent strikeout rate at Triple-A), but he is close to being ready to help the big-league club in some capacity. Thomas had a 5.47 ERA, 1.57 WHIP and 110 strikeouts in 135 innings across 28 appearances this past season.