Feingold lost because he was a bad Senator and Johnson ran one of the best campaigns ever. I wonder if Johnson can replicate some of that 2010 perfection. It is hard to tell because Johnson isn't a politician and has acted as such since he won and he may have been the perfect man at the perfect time, not a amazing campaigner ...at anytime.
Corporate money shouted in 2010 and 2014. It won.
It's the Koch syndicate that managed the general fight to transform the USA into a plutocratic oligarchy. Right-wing politicians who obeyed the money won. Now that more Americans know what is stake things can be different in 2016. Mediocrities win in wave elections and can get ousted in the next election.
They had better be, or America might be 'exceptional' mostly in having life-threatening poverty within the First World.