The role of a business analyst is to understand the big picture as well as all the details.
The big picture is what drives the project forward. Keeping the desired business outcomes in mind and aligning with those business outcomes increases the chances of a successful project.
It is in the details that we find the constraints, issues, roadblocks, anomalies, and other items that may derail a project. Oftentimes the client doesn’t see the value of understanding all the details until a detail is discovered that changes the course of a project.
Always keep the client in the loop with what you are doing and why you are doing it.