Most projects we come to for recovery or triage, we find there is a missing piece of the puzzle.
No one knows what actual Capabilities are needed from the system when it is complete, or even what incremental capabilities are needed along the way to the end.
A capability is defined and managed ...
Planning, under uncertainty, to provide capabilities suitable for a wide range of modern-day challenges and circumstances while working within an economic framework that necessitates choice.
By Identifying system capabilities, the elicited technical and operational requirements can be traced from the Measures of Effectiveness to each deliverable in the Integrated Master Plan and Schedule. Capabilities state the “why” of the system.
Without a clear and concise description of the needed capabilities, requirement - technical and operational - have no home. The system them becomes a solution to a laundry list of "stories," "needs," "requirements."
Agile is starting to address this notion through Epics, but the formal development of Capabilities is not found in traditional project management methods.
This by the way is where some in the IT business get confused about the "value" of Earned Value. Scott Amber for example, makes this mistake when he claims Earned Value does not represent business value. He is correct, but for the wrong reason. The term "earned value" in the ANSI-748-B paradigm was established long before the notions of modern agile "business value" were and therefore has a different definition. Both are needed, but 748-B earned value speaks to the amount of the budget that was "earned" at the time of assessment, versus the planned amount of budget for that same time.
Using the assessment of the capabilities is how you know that you are actually delivering Business Value. With the defined Capabilities, each Requirement now has a home, you know the reason for the requirement - the why are we doing this question.
Here's the Offical definition of Capabilties Based Planning from the ToGAF 9.1 source
Capability-based planning focuses on the planning, engineering, and delivery of strategic business capabilities to the enterprise. It is business-driven and business-led and combines the requisite efforts of all lines of business to achieve the desired capability. Capability-based planning accommodates most, if not all, of the corporate business models and is especially useful in organizations where a latent capability to respond (e.g., an emergency preparedness unit) is required and the same resources are involved in multiple capabilities. Often the need for these capabilities are discovered and refined using business scenarios (see Part III, 26. Business Scenarios and Business Goals).
From an IT perspective, capability-based planning is particularly relevant. For example, setting up a data center is really about consolidating corporate data and providing the related services. Lead enterprise architects for this capability will find themselves involved in managing construction, personnel training, and other change management tasks as well as IT architecture tasks. In the past, many IT projects were less than successful even though the actual IT implementation was brilliant, but the associated other tasks (business process re-engineering, client training, support training, infrastructure, and so on) were not controlled by the enterprise architects and planners and often were not satisfactorily completed.
On the other hand, IT projects were often described in terms of technical deliverables not as business outcomes, making it difficult for business to appreciate what was being delivered and often the IT architects lost sight of the ultimate business goal. Capability-based planning frames all phases of the architecture development in the context of business outcomes, clearly linking the IT vision, architectures (ABBs and SBBs), and the Implementation and Migration Plans with the corporate strategic, business, and line of business plans.
In many governments, horizontal interoperability and shared services are emerging as cornerstones of their e-Government implementations and capability-based management is also prominent although under many guises. In the private sector, the concepts of supply chain management and Service Oriented Architecture (SOA) are increasingly forcing planners/managers to govern horizontally as well as vertically.
It is the needed Capabilities that fulfill the Mission and Vision of their value proposition.