Except... that's not actually how this works? Every single person who's paying attention to this right now is already a fan of the series -- in other words, a person whose anticipation cannot, by definition, go up all that far. These are people you can either stun with a surprise announcement at E3 -- thereby ensuring an outpouring of enthusiasm from the existing fanbase at the exact time that potential new buyers are discovering it via media coverage -- or build up anticipation more delicately with an ARG-style teasing campaign, ensuring that fans build up the E3 conference in advance.
No game company ever, in the history of the industry, has decided the best way to reveal its hot new title is to release ugly, blurry, awkwardly-framed off-screen shots of their game on a message board, because that makes their game look bad.
"OMG it's a controlled leak" is something posters on GAF say because they really want to participate in a rumor-news thread and sound like they have something smart to say. In reality, controlled leaks are quite easy to pick out, and most of the time when we have one nobody feels the need to say so because it's already pretty obvious that a company-directed teasing campaign is happening.