There's no word yet on how long Valdez will be sidelined. Opening Day is less than a month away.
The 27-year-old sustained the injury Tuesday in a spring training game against the New York Mets, Kaplan adds.
Valdez is expected to be a big part of the Astros' rotation in 2021. He posted a 3.57 ERA with 76 strikeouts and only 16 walks over 70 2/3 innings (10 starts) last season.