Yamnaya and all other Bronze Age Steppe groups were heavy in R1a and R1b, which means they were paternally Eastern European.
They acquired their "Mediterranean" admixture from women from nearby farmer groups that came from the Balkans and the Caucasus.
Today most admixture from Yamnaya and related groups is found among Northern and Eastern Europeans. The least in Europe is found among Southern Europeans.
Not really sure why you're quoting Dienekes? He's stopped blogging on this topic for a reason.
Here's a freely available review of latest ancient DNA results. It's not that difficult to understand.
Tracing the peopling of the world through genomics
This paper references sources that are freely available online.