The role of a business analyst is to facilitate change the results in an increase in value.
According to IIBA
The Business Analyst is an agent of change. … Business analysis is used to identify and articulate the need for change in how organizations work, and to facilitate that change. As business analysts, we identify and define the solutions that will maximize the value delivered by an organization to its stakeholders.
With the focus on value, all the tasks that a business analyst performs are to help create some part of the change. Each part of the change should create more value than what existed before. In order to know the change is going to create more value, a business analyst has to take the return on investment perspective.
Use cases, requirement gathering, workshops, meeting minutes, models, relationships all lead to the change, the better the tasks are completed the better the change will be. Each individual task has an ROI in relation to the change that is being facilitated.