Why did X-Men: First Class underperform at the box office?

We quite liked X-Men: First Class, but sadly it failed to levitate the box office with the power of its mind. The mutant prequel made just $56 million in its opening weekend, less than the $69 million some analysts predicted.

What happened? And can the X-Men still claim a victory somehow?

First of all, a few bits of context:

The movie did slightly better than the studio's own prediction, but much worse than some outside analysts expected. And compared to other big summer movies, it was kind of anemic. Also, consider that X-Men Origins: Wolverine made $85 million in its opening weekend. And X-Men: The Last Stand made $103 million in its first weekend.

X-Men: First Class did great overseas. Of course, by all accounts, Hollywood weights U.S. box office more heavily than overseas box office, because the studios get a greater share of domestic gross.

The movie may have a great second weekend, which was what helped Thor become a huge hit stateside. The only real challenge to X-Men next weekend is Super 8, which may be a smaller movie as well.

That said, what are some reasons why X-Men: First Class may have underperformed somewhat?

It wasn't in 3D. Which is cause for major rejoicing, especially since it wasn't filmed in 3D. But you know that many movie-goers would have coughed up an extra $5 to wear clunky plastic glasses and see the movie looking slightly worse.

It was the fifth X-Men movie, and the last two sucked. Counting Wolverine, this is the fifth movie in a series that's been cranking them out. It worked for Fast and the Furious, but only because the fifth movie brought back everybody. And it's possible that casual audiences remembered just how agonizing X3 and Wolverine were, and decided not to give the mutants one more chance. Sometimes, a crappy movie can be a hit, but you still pay the price later on.

Why did X-Men: First Class underperform at the box office?

The marketing was godawful. I mean, seriously. Remember this? And this? They basically rented out a billboard saying, "Total cheesefest. Nothing to see here."

It was too geared towards X-Men fans, and not enough towards random X-neophytes. At least, that may have been the perception. The whole "find out how Magneto got his helmet" thing the trailers focused on. It may have looked too much like fanservice, and not enough like a mainstream movie that assumes you know nothing about X-lore.

Nobody famous was in this one. Sorry, James McAvoy and Michael Fassbender. The lack of A-list Hollywood actors may have been the real reason huge crowds didn't show up for XMFC. So you can expect to see Hugh Jackman (or someone equivalent) in every X-Men film from here on out.