As +Craig Addyman
says at the end of the post, there are variables that may have had a more significant impact than just adding your authorship, +Rand Fishkin
For instance, the same showing 10 posts in home page and not 100 anymore is a huge change, because those 100 links (plus all the others usually present in the HP) were drying the link equity the home page passed:
1) to the same internal links present in the home;
2) to the internal pages/section of the site.
Reducing that number, even if the post with your authorship wasn't anymore in the home, probably gave a better link equity to the post URLs itself.
Then, there the date change... and blog posts - especially when a blog is getting traction from an indexation point of view because of its increased new postings - are strongly biased by Freshness... and I can imagine that queries like "Interview with..." "Interview about..." etc etc are those kind of queries that are affected by Freshness.
Beside all this, it is still a good experiment, that maybe should be backuped by others in a more "neutered" conditions.