Scroll any agency site and you will find the same case study: hero image, three mockups, a paragraph about “bold visual language”. It proves the work exists. It does not prove it worked.
Show the constraint
The interesting part of any project is what was in the way — the budget, the timeline, the category convention you broke. Work without a stated constraint reads as decoration.
Show the number
Reach, conversion, sell-through, sales-cycle length. Pick the one the client actually cared about and put it in the page. If you cannot share it, say what changed and why the client stayed.
Show the thinking, in order
Challenge, approach, direction, execution, result. In that sequence, a reader can follow the logic and imagine their own problem inside it. That imagination is what books the call.