I was just getting started in Local SEO (2007-8) and was exploring the many questions about local ranking, etc and Bill was one of the few that seemed to be writing anything at all about local seriously. He would post on my blog and I would often post on his. Our relationship developed and for many winter weekends he, Matt McGee and I would send each other long emails about search results that we were seeing, trying to understand what was driving what.
He and I decided to emulate an early SNL skit "Point/Counterpoint," with Dan Aykroyd and Jane Curtin where we would take strong opposing positions on a topic to see if we could generate blog comments and interaction. On the question "Could Local ever get its data issues together and present reliable lists of issues" he took the con position and noted that he didn't think that Google was good enough at data aggregation to ever resolve their data quality issues. It took Google totally revamping their architecture to prove him wrong.
He made me aware of the Google Local Search Ranking patent which provided the basis of the whole industry's understanding of citations, reviews, links, mentions etc as ranking factors. It was that patent that ultimately provided the cored ranking in the Knowledge Graph and provided me with a global understanding of how Google local's ranking algo actually worked.
He was an instrumental partipant and mentor to my career. He will be missed