Honestly what kind of world do we live in when below average stuff like Man of Steel and Star Trek into Darkness makes a ton of money and good movies like Pacific Rim gets ignored.
Warner Brothers dropped the ball big time IMO in marketing this film. For a film with zero name recognition I personally didn't see even one commercial for it on TV.
Also, they missed a huge opportunity to tie in a toy with a major fast food chain to also build the brand and interest.
The lack of big name stars for an unknown franchise also hurt its ability to attrack an audience.
All in all - WB has only itself to blame for the failure of this film IMO.