I watched a similar thing happen once. A greybeard was brought in to whip things into shape. He did so. Automated everything and made 100+ linux boxes run like a top. New owners came in, and they weren't the nice kind. He got stressed out and had a heart attack and was gone for several weeks. Things hummed along while he was gone, and his perceived value went down because things "ran just fine without him", ignoring that it was because of him.

They ended up firing him and giving me his responsibilities, which was a laugh because he and I had drastically different jobs, and he was far more experienced and capable in system administration and automation than I was. I too left less than a year later.