On the other hand, this early version of Sanders appears to be an eerie carbon copy of the Howard Dean 2003 campaign—wildly popular with the party's white, educated, middle-class base ... and few others.

The most recent CNN national poll had Sanders getting 19 percent of the white Democratic vote, and just 9 percent of the non-white vote. Clinton's numbers were the opposite, getting 53 percent of the white vote, but 61 percent of the non-white vote. Given that non-whites will make up around 40 percent of primary voters, Sanders needs to gain with those groups if he is to have any shot at the big upset.

And that's not even considering the huge gender gap already emerging. In that CNN poll, Clinton gets 50 percent of men, and a whopping 63 percent among women. Meanwhile, Sanders gets 20 percent of men, and just 9 percent of women. We see that same gender gap in Iowa, where Clinton gets 46 percent of men and 56 percent of women. Meanwhile, Sanders gets 37 percent of men, and 29 percent of women.

Being a white male is finally a disadvantage somewhere.

Clinton benefits from an age gap—in the CNN national poll she gets 61 percent of voters over the age of 50, and 53 percent of those under 50. Sanders is stronger with younger voters, which is exciting, sure, but a group of voters not generally inclined to vote.

And then there's education. Sanders gets 19 percent of the vote from Democrats who have attended college. But he gets just eight percent from those who haven't.

So younger, whiter, more male, and more educated. Yup, that's the Dean coalition, and unless Sanders can bust beyond it, his fate will be the same as Dean's.

Further making Sanders' life difficult is the fact that people like Clinton. In Iowa, her favorability rating among Democrats is 85-10. Even among "very liberal" respondents, she's 88-7. Ironically, it is among conservative Democrats that she suffers relatively, at 82-11.

Bernie Sanders is also popular at 66-8, and the 26 percent who haven't heard of him will eventually slot in as "favorable" because who the heck are those 8 percent who don't like him? So in short, we have two very popular Democrats running against each other, neither showing any willingness to go negative on the other.

So with Clinton still comfortably over 50 percent, even in Iowa, what is Sanders' path to victory against a popular opponent? He can go negative, but he's laudably rejected that approach and I wouldn't bet on him reneging. Meanwhile, it is difficult for him to make inroads among women who are understandably excited about finally getting a woman president.

Lucky for Sanders, he doesn't have to deal with Latinos and African Americans until later in the primary calendar, but he's going to eventually have to make inroads among those groups. Still, I remember being caught up in the energy and excitement of the Dean crowds back in 2003, only to see Howard crash and burn when voters and caucus goers cast their ballots. It's one thing to get big crowds in college towns like Madison and Portland, Maine. It's another to grow beyond that.

For now, though, Sanders has been the beneficiary of Clinton's timidity on economic issues, exemplified by her refusal to oppose TPP. Not only was that politically stupid, giving Sanders a shot in the arm, but policy stupid. If Democrats aren't willing to stand for the working class, what the hell is the point? She would've lost very few votes by standing strong against TPP, but instead, she stoked latent distrust among the party's activist base. Quite stupid, really.

But aside from all that talk about polls and demographics, let's take a moment to reflect that now, over a year out before the election, thousands of Democrats are turning out to rallies and events. Can a single Republican show similar excitement?

Of course not. The energy and excitement is on the Democratic side, portending a very good 2016. The more Clinton and downballot Democrats tap into Sanders' message, the better the year will be.