Sanders' argument that he's simply less familiar to voters of color certainly holds weight...but it isn’t just familiarity with Clinton that is swaying voters of color into her camp. It’s also the effective case she is making that she has the best chance to get things done as president—a case that Sanders has not yet made effectively. - Jamil SmithSmith may try to hedge against criticism with vague caveats about how Sanders' explanation "holds weight", but none of that nuance prevents him from arriving at the same position he always does: that voters of color are rejecting Sanders' substantive platform.
Still, we don't have to read several thousand words of speculation and conjecture from Smith to figure out what's going on: we can just look at the polls. (Are you noticing a theme here?) From the latest Yougov / Economic crosstabs:
It's true that Sanders has lower favorability ratings among black and hispanic voters. However, that discrepancy can easily be accounted for by the disproportionate number of black and hispanic voters who simply don't have an opinion about him at this point. And in fact, if you split those voters proportionally between "favorable and unfavorable", Sanders takes a lead among every demographic but Hispanic voters, where Clinton retains a slight edge.
These polls do nothing to substantiate Smith's elaborate theories about what voters of color are thinking, though they do happen to conform to common sense. Beltway media editors are immersed in a world of controversies over Ta-Nehisi Coates articles and Iowa ad messaging, but the overwhelming majority of the country simply doesn't care about any of this yet. Clinton's slight edge among Hispanics is worth paying attention to, but it would be premature to draw many conclusions at this point; if the data tells us anything, it's that Sanders' theory that voters still don't know him very well is probably right.