The skills required to think through in detail the efficient implementation and modification of our business processes are usually only developed as a result of significant experience and study over a period of years. Although we each possess some of the skills to one degree or another we tend to focus on the areas we understand or are comfortable with at the expense of other areas.
The role of a business analyst encompasses all areas and is defined by the International Institute of Business Analysis (IIBA) Body of Knowledge (BOK) as "A business analyst works as a liaison among stakeholders in order to elicit, analyze, communicate and validate requirements for changes to business processes, policies and information systems. The business analyst understands business problems and opportunities in the context of the requirements and recommends solutions that enable the organization to achieve its goals."
In other words a business analyst is required to have a detailed understanding of the whole business operation including its people, processes, policies, information systems and the environment. Because of this comprehensive overview the business analyst is in a position to assess the impact any changes are likely to have on each of these areas and is therefore able to develop and implement workable solutions to business problems.
In simple terms a business analyst is trained to think about, work with and document all the details involved in making changes and improvements to our business processes and information systems that would probably overwhelm us if we were to try doing it ourselves.