I'm just looking at it from two possibilities:
a) The build is a recent one, which implies the game still has ~65% to be done within 6 months.
b) The game had a typical game development schedule, in which case why the buggering heck would they bring such an old build to E3?
I can't be the only one who finds the '35%' comment weird. The game's have to go gold in less than 6 months, too.
But that's simply personal incredulity. If you have to ask the question "why would they bring an old build" then you don't have enough information to come to the conclusions you're coming to.