But, you want to go into information, here is God of War: http://en.wikipedia....%29#Development
It started development in 2002, had a demo release in 2004 (which was bugged) and was finally released as a finished product in 2005. This, too, was a single player campaign game, with no online play that I am aware of. Online play only games become more difficult. This game took 3 years from start to finish, and was made for single player only, so balance was not much of an issue as it would be here, in an online player vs player environment.
God of War 3: http://en.wikipedia....III#Development
It was started in 2007. Finished in 2009. Single player game again. Same creator, and probably some/most/all same staff as previous games, making development faster. No online content that I am aware of again.
Guildwars 2: http://en.wikipedia....s_2#Development
Started development in 2007. Closed Alpha/Beta tests in 2011. Full release to the public was in 2012. 5 years here, and it has single player campaign, player vs player, world vs world... This is probably more what MW:O should be compared to, as it shares the most qualities with it. And this team also had previous experience from working on Guild Wars (1)...
I don't think you would want to know how long it would take me to sketch out the web site background, of course that also is already predesigned and created, and doesn't relate to creating something completely new from scratch...

Anyway, to reinforce the concept, a game takes anywhere from 2-6 years typically. MW:O isn't even into year 3 from the sounds of it so it's time table isn't too far off right now. They've had their problems which slowed them down, and inexperience sounds like it didn't help much either.