Possible Clues:

• Discreetly, in slang
• Hush-hush
• Officially injured, in previous baseball lingo
• Out of action, in baseball lingo
• Temporarily out, in baseball lingo
• Discreetly
• Under wraps
• One way to be out, in MLB
• Hush-hush, slangily
• Discreetly, informally