Newsom may underperform Brown '14 by a good bit. Still obviously Safe D, but I think Travis Allen would've put up a bigger fight than Cox is.
I actually think the opposite. Allen's style is a little more polarizing in the vein of Trump, while most of the attacks on Cox would be his very conservative (for California standards) ideology. I don't think Cox will win, but losing in the high single digits or low double digits wouldn't surprise me much at all. In a Hillary midterm, this might actually be a winnable race for the Republicans against Newsom.
What do you think is more likely- republicans winning a statewide race in California when they couldn't even do that in 2010, when the state was less democratic, or this poll being sort of junky? Be honest with yourself.