The core concept of Solution refers to the assessment of the performance of a solution and determining whether it is delivering the potential value. It is also about determining why a solution may or may not be delivering the value that was expected. 

Let's continue our example of Debby's Unique Dresses to see how the concept of Solution works in the real world:  

The potential value in the form of increased sales for Debby's Unique Dresses was not realized as expected when the new e-commerce solution component was added to the existing website. The role of the business analyst is to analyze why this value was not realized.

This example illustrates how the core concept of Solution should be assessed in terms of its performance when attempting to deliver the expected business value.