I am just guessing like everybody else but it seems like SE's now and not just Google for some reason, are not using the META tags anymore. They are trying to come up with some sort of intelligence of their own to decide what the page is about. I reported a while back in a post that disappeared that I had a page with widgets in Montana and the only thing Google had in the title was "Montana - Domain.com", the description was a mash-up of things on the page. It was weird.
What I am seeing now is that most of the time I get hits from a 3-4 word search. The words can be in different order and they can have synonyms but that's it and that's not what I am expecting. There should be other at least long tail searches that my site shows up for but it seems like Google have decided that my site should be within those 3-4 keywords and nothing else. Weird.