The question Are they playing ball? might refer to children playing in the street, or to business people. In the case of business, the question means: Will they work with us? There are many sports idioms used in business settings that use a wide range of sporting vocabulary such as verbs used with sports, equipment, fields and courts, and so on. If you are in business, it's a good idea to get your game on (make your best effort) and learn this vocabulary.