That's a shortened version of the clickbaity headline of a post over on the Motley Fool website, the authority on comic book movies.
The article and accompanying video say that an "Avengers bump" helped Captain America: The Winter Soldier reach over $300 million worldwide last weekend. One of the analysts says that Guardians of the Galaxy doesn't have the same direct tie-in which may hurt it (or at least make it not as successful as CA: TWS) at the box office.
I'm not a comic book guy and knew nothing of the GotG before the movie was announced but I think it will do just fine at the box office.
The first ~8 minutes of the video below covers Captain America (and Scarlett Johansson's flatness). If you don't have that much time the article can be found here.