I went to the Cuyahoga County website and downloaded 2008 and 2012 Presidential election data. I sampled “CLEVELAND-01” precincts. Frankly, the results were similar. In both cases many precincts only registered 5-10 total GOP votes. Not sure if any of this is really new...
I've seen this in real life, it's not new. In the black community, they do two things. They go to Church on Sunday and vote Democrat. I've asked blacks in the inner city why they vote Democrat and you'd have thought I told them Jesus wasn't real. It's generational. Same way in Cleveland and Philly; blue collar folks of every race vote Democrat. It's not about the issues, it's tradition and regular as clockwork.
IMO what is really changing the turnout and defeating conservatives is an entirely new generation of voters that have been indoctrinated in public schools. The left has defined Republicans as greedy white people who don't want you to have sex or get an abortion when you get knocked up. They are anti-capitalist and want something for nothing.