Let me get you up to speed... In October, Matt Cutts said there will be a 15% reduction in authority to only show authorship and rich snippets for authors who have a higher level of authority. That actually went through in mid-December and I hear complaints every single day from site owners that their rich snippets and authorship is gone.
Bill Hartzer and Mark Traphagen are having a conversation on Google+ where they say that it doesn't seem that the authorship reduction has to do with author authority. In fact, they say it does not have anything to do with author authority.
Mark Traphagen said it may be more related to the "publisher authority or quality."
Truth is, that is probably right. Because when Matt announced it in October, it was aimed at all of rich snippets, not just authorship. It was aimed at the quality of the site.
Now, Matt said his team is also working on author authority but that has not officially rolled out yet.
So at this point, I'd agree - the authorship reduction might not be related to author authority but rather website authority and quality. But in the future, it may be author specific.
Forum discussion at Google+.