Business people and developers must work together daily throughout the project.
Many many years ago, I was part of this offshore maintenance project for around 2 years. During the first year, we were a team of 3 – a project manager (PM), a technical and documentation lead (TDL), and a developer(DEV). I was the DEV. The PM had to interact with the client in getting new requirements, change requests, defects and prepare a plan for them. The TDL was in-charge of conducting feasibility studies, preparing implementation proposals and relevant documentation. The DEV had to implement it. I guess you can already understand the problems with this setup.