Oversaw a game

• Made calls, in baseball
• Worked on a field
• Called "Out," say
• Officiated, shortly
• Inspected diamonds?
• Called strikes and balls
• Helped out at a T-ball game, perhaps
• Refereed, shortly
• Officiated on the court

Wiktionary Word definitions in Wiktionary
vb. (en-past of: ump)