?? This poll had Clinton at +93 among blacks, better than Obama 08 and matching Obama 12. It also has democrats doing worse than her among blacks in 2018.
It is not a poll, it is aggregation of sophisticated individual-level voter modeling using the best available methodology and data.
Correct, it has her doing as well as Obama '12 and better than Obama '08 among African American voters. If you think that is wrong, while it is indeed quite possible it could be slightly off by a point or 2, it is more likely to be your assumptions that are wrong.
As for why Dems would do worse among Blacks in 2018 than 2016, the likely explanation is that this is comparing Congressional vote data to Presidential vote data. In congressional races, a lot of races are not seriously contested and have lopsided vote results, because the challenger is not a serious candidate/doesn't get funding to run a serious campaign. In those sorts of races, Black voters (like voters in general) are more likely to vote differently than in Presidential races. In addition, in midterms the African American electorate is older and higher income than in Presidential years, which tends to make it slightly more GOP-friendly (you can see similar patterns in the 2010/2014 data).
