You can't communicate experience like you can communicate theory, if you could then it would be called theory instead of practice. Theory is great since it is something we can communicate, whatever instincts you developed working on a big codebase can't be communicated. Some people thing you can, there are lots of talks about these things etc, but in practice you can't teach practice, you need to experience it yourself. And if you distil practice into pure enough droplets of wisdom that others can recognize as the truth without being your in-group, guess what, that is what we call theory!
Talk about how the candidate used technology X in practice, what was their role in the project, what worked in practice and what not, how they would approach the bad decisions in retrospective of the lessons learned while using X.
