Astros manager Dusty Baker acknowledged Tuesday that Castro is "ailing," though the skipper didn't go into specifics regarding the backstop's recent absence from Grapefruit League games, Chandler Rome of the Houston Chronicle reports.

EDGE Analysis

Castro hasn't caught in a Grapefruit League game since last Thursday and remains out of the lineup for Tuesday's contest against the Nationals. Assuming whatever is keeping him off the field isn't a major concern, Castro should be ready to go for Opening Day. He's in line to serve as the primary backup to No. 1 catcher Martin Maldonado, a role that will likely afford Castro anywhere from one to three starts per week.