There are overwhelmingly more people on the site saying quality has degraded sharply --- most of them citing politics as one of the reasons --- than there are people defending it. Also, a close look at the people who do defend the current quality of the site might be instructive.
Are you sure it's IQ, or as another user suggested, some kind of mass hysteria?
The mainstream news exploded with the whole NSA thing, and then HN did too.
Is that a function of IQ?