It is very useful for a business analyst to know which roles a particular stakeholder or group of stakeholders plays within the organization. This will help the business analyst to determine their influence later on and will help in planning the engagement type required for that stakeholder or group. 

For example, in a project where the solution will mean a different process for customers when using Automatic Teller Machines (ATMs) to get cash out, it is important to not only identify the customers as key stakeholders to engage with but also the customer support personnel who would need to support those customers during the change and transition period. If the project doesn’t identify the customer support team as a key stakeholder group due to the role that they play in the overall proposed changes, the risk of failure increases dramatically for the project.