For the really big-budget films, the North American box office gross does not always have to be spectacular. International is becoming a bigger part of the pie and so are worldwide video sales.
Right now studios are just happy to break even at the box office.
When it's the right film with the right story and the right star, then you've got a box office hit on your hands. Often times they are very profitable movies because the budgets aren't very high; it's a matter of targeting the audience and reaching out to them.
Even if you get a nomination for best picture but have no chance in hell of winning you can reap incredible profits at the box office.
This helps save them from times when they have a drought at the box office.