The MNCBA also tipped me to this good article: Burned at the box office.

It analyzes how all of the movies debuting this summer had a second week drop-off in attendance. Industry execs brush this aside as the “new blockbuster paradigm,” but there’s just no way that can be true. Good movies get good word of mouth and the people you tell usually see them the second weekend. If this isn’t happening…it’s because there aren’t that many good movies to see! If everyone is telling their friends and there is a drop-off, the word of mouth is not good. Not exactly rocket science.