The point of this diagram is first of all to highlight the three basic activities of information systems, so that students can understand what an information system is doing at its most fundamental level. But the diagram also puts information systems into the context of organizations (firms), and then puts the firm into its respective environment composed of shareholders, higher level authorities (government), competitors, suppliers and customers. Suddenly students should see that information systems play a central role mediating and interacting with all these players. Hence, systems play a key role in the operations and survival of the firm.
You could also explain this diagram by relating it back to the opening case, as the book does. The two types of input into the Synergy system are manually entered data as well as video. The system processes that data and creates the output, video and statistics about specific types of players and plays.