Work breakdown structures (WBS) are for project managers to help in managing time and scope.
The contribution that a business analyst makes to WBS is understanding.
For the discovery phase, it is key for a business analyst to break the overall domain into components for analysis.
For the design phase, it is key for the business analyst to break the design into a manageable set of components for development
For the execution phase, it is key for the business analyst to break the design into a manageable set of test cases to prove the design delivers the appropriate outcomes.
In all cases it is important to strive to have each component be:
- Independent
- Able to be completed
- Organized
The better the components are understood the greater control the project manager will have in planning the components taking into account time, quality, and money.