The 25-year-old left spring training and flew home to the Dominican Republic without telling the team, which found out he was gone a few days later only when another player told staff.
Munoz was dealing with a hamstring injury and ended up missing a scheduled examination when he left the club. He was on the team's 40-man roster and thought to have a good chance of breaking camp in the majors. Cardinals manager Mike Shildt called the situation "baffling."
The infielder appeared in 196 games for the Cardinals over the past two seasons and posted a .273/.331/.391 slash line with 10 homers, 55 RBIs, and 13 stolen bases. A shortstop by trade, Munoz has played six different positions during his brief major-league career.