Note: I voted for Clinton. I phone banked for Clinton. I donated to Clinton. I did vote for Sanders in the primary.
First off, again, I'm not saying "Bernie would have won." It's a foolish thing to say, as is making a declaration that he wouldn't have. Who knows. I just think that, based on the evidence I've seen, he had a better shot if unimpeded. That's an important point. There's a chance that Bloomberg would have stepped in had Sanders won the primary. The effects of this are impossible to know, but my guess is that it would have handed Trump the presidency on a platter. In a pure Sanders v. Trump race, however, yes--I think he could have done better. Perhaps significantly.
These are the basic reasons I think Sanders had a better chance, in no particular order, though I'd definitely put #6 last:
1. Polling numbers
2. The mood of the electorate
3. The midwestern states that decided the election, and the very small number of votes that decided their outcome
4. Clinton's significant weaknesses as a candidate vs. Trump, particularly in those states
5. Sanders's strengths as a candidate vs. Trump
6. My own anecdotal observations
First, the obvious. There is not a legitimate argument that Sanders was not doing significantly better than Clinton in national polls vs. Trump. This data is not terribly important in January, but into the summer it gets more reliable. Enough to cover the historic margin of error, even if it were way off the mark:
The last time they conducted this sort of poll, Sanders had an average 10.4% lead:
Clinton had about an average 1.6% lead:
I'm very aware of Eichenwald's (uncited) opinions. Some are valid. Other's I very much disagree with. And, like most partisans, he completely ignores other, much larger factors to validate his world view.
No doubt some would have had an effect. As would the line of attack Sanders was uniquely suited to make against Trump that Clinton could not because of her record, both real and imagined. Sanders stealing electricity in his youth vs. the enormous effects of the server scandal, or Sanders's "rape" quote against the enormous effects of Trump's history with women. The only one that could have caused him real headaches would have been the nuclear waste issue. I'm not convinced that this would have convinced Hispanics to vote Trump. Hell, some of the Trump crowd might have thought that was a plus.
I don't see these issues erasing that advantage to a degree that he would lose. Obviously we're dealing with Trump, however, who has absolutely no shame, so who knows what crap he would have made up. Considering
The exit poll also does not mention how gender played in decision making which, while not moral, likely had a negative effect on Clinton.