I have a couple of ideas you could chase up.
First, there's a post
here that talks about being dropped by Google due to being hacked by a spammer. It also has some advice on what to do.
Second, it seems you're using StatCounter, which I used to use years ago. I think you've got it set to 'invisible mode' and from what I heard, Google doesn't like anything to be hidden to the human eye on a page.
I'd replace StatCounter with another stats system. But I'm not totally sure this is the reason, or if what I just said is totally true. It's worth looking into, though. Maybe even just making it visible would solve the problem. I don't know.
Third, just give it some time. Maybe Google is just doing a Google dance or something mysterious and when the dust settles, your position will rise again.
You're still actually in the index, right? I'd only start to really panic if you were completely gone from Google altogether.
Good luck!