I don't doubt some tone-deafness on our part contributes, but in my opinion there are some more important factors. Clinton has been incredibly popular among black voters for a long time. A lot of older black folks I talk to remember the Clinton economy very positively, for example, even going beyond their general personal like for the man. Undeniably this for black employment, home ownership, etc. it was a very good decade coming off the Reagan-Bush years.

Sanders went on a lot about the since controversial criminal justice reforms of the Clinton era, but it came off sort of like Republicans who think passing Immigration reform is the only thing they need to do to salvage their image among Latinos. I'm not at all upset he was willing to raise those points, but he needed to remember there's more to winning black votes than talking about how you marched with Dr. King or criminal justice reform.

I'd also add that, while an economically populist message can resonate with black primary voters (see Jesse Jackson) there are plenty of black voters who aren't particularly left-wing on economic or even criminal justice issues. Bernie being pro-welfare, in favor of criminal justice reform, or wanting to toughen financial regulation isn't going to resonate with many of these voters without an effective pitch, that I personally thought was lacking throughout his appeals to Black voters despite being a longtime supporter. And to be clear the Democratic party is a big tent. You can't just convince people who like the remaining vestiges of the New Deal, Great Society, and social democracy generally if you want to win the nomination. You have to broaden your pitch or pitch those things in a way that attracts a broader constituency. He certainly tried and black voters definitely found him incredibly wanting. Those of us who want the left of the party to do better need to do better ourselves.