Yeah it's easy to see that you put a lot of effort into your blog and presence here and even though comment engagement varies over posts as it should on average you do really well in terms of engagement and the rewards also reflect on it both through autovotes and manual votes.
Some people however once they get to your position, decide now's the time to retire from "trying", they stop responding or only respond to comments on their own posts, set an autovoter only so they don't have to bother with that, eventually stop replying to comments altogether and the comments decrease over time but the autovotes remain the same. That's what I imagine happened to that user or they're receiving votes for other unknown reasons and they never "deserved it" to begin with.
It's always a little discouraging when the auto vote service is down and you realize just how few people actually read and vote on your posts! I appreciate the benefits of auto voting, but I also like doing some manual stuff too. I know we have talked about it before, but more recently, I am really loving voting on comments. It's a nice way to give back and show appreciation I think.