The 22-year-old reliever has been solid in 2019, going 2-2 with a 3.14 ERA, 0.94 WHIP and 31 strikeouts in 28.2 innings.
He's also posted three holds and 14 saves in 15 chances, emerging as the team's top closer. He suffered the injury during Saturday's 4-2 win over the Los Angeles Angels after pitching 1.1 innings.
Hicks is an ascendant flamethrower who hit an incredible 105 MPH on a fastball last season, though with Tommy John surgery potentially on the horizon, the concern will be that he could lose some of the sting in his heater.
It's also possible that Hicks could rehabilitate the injury without surgery.
According to ESPN.com, "The 22-year-old has thrown 211 pitches at least 100 mph this season, over 100 more than the next closest player. Last year, Hicks threw 673 100-mph pitches and became the only player in the last 10 years to throw 500 or more 100 mph pitches in a single season."
With the team's starting closer now sidelined, players like John Gant (three saves), Giovanny Gallegos, Carlos Martinez (two saves) and Andrew Miller (one save) could all audition for the role. Regardless, it's a major blow for the bullpen and a setback for the 40-37 Cardinals as they fight for a playoff spot.