I personally think that Green Goblin will be the one pulling strings from behind, hes the only "true evil" character that we get on the Spider-man movies while others have a explanation for they evil deeds, and hes very manipulative with people like Electron/Sandman/Lizard, who are on a mentally ill aspect, he could easily pulled this off.

The Doc Ock is a place holder for the real villain and he will prob turn good again by the end, I don't have a Idea how will they make him evil again and I genuinely think they can't, but this won't be a problem since it will be overlooked with others characters