Here's why Hillary won the primaries on her second try, but Bernie probably won't.

The first time Hillary ran, she ran against Obama. Many of us would have been happy with either one as President. (I didn't even go to the caucuses that year because I liked both of them equally.) Then Obama, after he won, made her Secretary of State -- giving us all even more reason to support her next time. And she waited to run again till Obama had finished his two terms, so the voters who preferred him didn't have to choose between them.

Bernie lost to Hillary by 4 million votes. To win a majority this second time, he's going to have to get millions of votes from Hillary people. How many of them are going to pick the man who is STILL railing against the "Democratic establishment" and against Democrats like Hillary? If he only wins a plurality, then the winner will be chosen at the convention -- the electors will choose the nominee in subsequent ballot(s). What are the odds that the electors will choose the candidate with a minority of votes who rails against the "establishment"?

Which is more likely? That voters/electors who preferred Hillary will pick Sanders this time -- or that they'll pick Warren, Biden, Klobuchar, etc.?

We will win when we put somebody on that ballot that excites the base

That's propaganda not journalism.