A Question About Google PageRank

Pardon the navel-gazing, but I have a question for readers who are reasonably well-informed about Google PageRank. For a long time, the Volokh Conspiracy had a PageRank of 8. A few months ago, around the time we switched to Disqus comment threads, our PageRank fell to 4. It’s not the world’s most pressing issue, but I’m curious if any readers know (a) why we dropped and (b) whether we should care that we did.