PROOF: Big Bang - December 7th

So can someone tell me the benefits of releasing a Massive patch on the same day as a bigger (imo, better) game releases a massive expansion?
lyke business wise, coz i wanna know.

For same reason as it goes for video game consoles and TV programs. They want players to make a choice. It's not a surprise anyways, that companies for December season.

Bigger as in? They have ~12million players worldwide and MS has 95million registered users. Their profit is about the same as Nexons (Nexon 2009: $571,100,000+). It is hard to tell MS playerbase, because MS happens to be free2play game. Free is also a huge advantage for MS.