Mundell was placed on the restricted list Friday, Andersen Pickard of MLBDailyDish.com reports.
A reason for the transaction wasn't given, though Pickard notes that players who elect to opt out of the season are placed on that list. Mundell isn't high on the Rockies' depth chart and has yet to make his big-league debut, though he did hit a strong .333/.399/.521 at Triple-A Albuquerque last season.