User blog comment:G0LD3NF1RE/Dawnguard encounters issues with Playstation/@comment-4248410-20120907234104/@comment-3202167-20120908055413

DNF was stuck because they kept changing devs, kept changing engines, until they finally settled and just released it. It would make tons of cash anyways.

While coding is not step one, I am more than sure they did not spend 4 years on concept and 1 year on coding.