Related Clues:

• Plate cleaners
• Calls balls and strikes
• Boo targets, sometimes
• Experts on plays
• Refs' kin
• Diamond experts?
• Foul callers
• Diamond V.I.P.'s
• Game callers
• Diamond quartet, briefly
• Boo targets, often
• Baseball officials
• They know when you're out
• Court judges
• Softball officials, briefly