Amitesh,

In my experience it is difficult to use a new technique on a real project, specially when someone else is telling you it is the right one. As a BA, I first need to understand the business and software environment using any technique which makes sense to me. Once I feel like I have a basic understanding I can use another technique to present my findings. I would encourage you to use process identification, workflow diagrams, sequence diagrams, or anything else that helps you get a good feel for the project. These can just be sketched on a piece of scrap paper or a white board. Once you understand the system, think about who you need to present it to and what presentation format will be most useful for them. If your senior BA wants to see a DFD, you can give him one. I love DFDs but also recognize not everyone does. If you are going to be presenting your findings to business stakeholders, another approach may be better. All of these analysis techniques should help us analyze, not force us into a diagram or deliverable for the sake of the deliverable. 

Hope this helps,

Barb Carkenord