KPI to measure full impact of self-service strategies

My organization is familiar with traditional measures of case deflection rates, however, as we develop better and more proactive strategies, we need to evolve this metric. In previous organizations, I've used an all-inclusive Help Center abatement metric, where we could tie all Help Center sessions/customers to all contacts, so regardless of Search, or the customer clicking a "yes, this helped me" button, or abandoning a ticket mid-flow, we captured the full experience of a customer that interacted with the Help Center in some way.
I'm looking for alternative ways to measure the success of the Help Center, besides case deflection rates that are tied to a sub-set of experiences (search, clicking the thumbs up, etc.). Is there a better metric that will account for all experiences in a Help Center (like adding a chatbot)?
Edit: Let me expand on our Help Center experience too, we offer KB articles (and will eventually offer a chatbot) outside of the "submit a ticket" experience, so I want to include the entire self-service offerings in our calculations, and not just the abatement/deflection seen from the ticket portal.