Who should take the blame for this year offense, Mills, Pep, Lovie, or OL?

I mostly blame Pep since Mills played well last year. And Showed only 2 games that he could do something (Raiders and Colts). So my guess is that Pep is holding him back.

I also can't say that Mills isn't the blame, of course he played terrible. But he played worst than last year, that what I'm trying to say.