Aware of that but that 'minimum' implies a best guess at the time. They wouldn't say a minimum of 5 minutes when they know a player had been down with a head injury for 15 minutes in normal time. Additional time beyond the minimum is usually accounted for by a sub, injury, etc after the announcement of the extent of the injury time.To be fair it's not four minutes it's a minimum of four minutes
edit: It seems Perez was subbed in injury time.