What could Sanders have done differently to win the black vote?
I said it before and I'll say it again. You didn't like it when I said it then and you won't like what I say now.
Bernie showed up in many states a virtual unknown to most everybody. He wasn't prepared to make the total effort needed to win over a justifiably skeptical black vote. That article stated clearly that there weren't enough resources available to his team specifically tasked with reaching out to the black vote. It was unrealistic that an old white man from Vermont could just take the same message to the whole country including southern black voters and get them to switch from Hillary after a few speeches. Hillary had built a relationship with that key delegation in the party and Bernie didn't give his effort enough time or resources to convince that group of voters to switch. I think he did the best he could with the time and resources he had but it wasn't enough.
I voted for Bernie and was a supporter early on. I followed the election just like others and to my eyes Bernie babies complain about the nomination "being stolen" when the reality is Bernie lost. A big reason was that he failed to garner much more than 10% of the Democratic Party's black vote.
But really, I might as well be talking to a Trump supporter. You aren't listening.