Yes you are right. Now I also see that Vovnigi and Derevka are the most likely candidates for PIE.
These people from the Vovnigi and the Dereivka probably ancestors of all the existing Indo-European peoples.
CW and BB (geneticly and partly culturaly in BB case) probably come from there. And even the historical Hittites, which some researchers derive from the Sredniy Stog. And languages we are speaking now, began to disintegrate precisely there and in those times. The rest of the vast territory of possible PIE languages (as the eastern yamnaya), did not have offspring of historical IE speakers. Therefore, we can not say in what language they spoke, although their cultural characteristics were identical to IE.
The source of these burials Vovnigi and Derevka is somewhere on the Popovo-Zvejnieki mesolite line.
Apparently, there began process of absorbing EEF genes, which are presented in CW.
Probably, they took women as trophies during the devastating raids on the neighboring Tripolye and the killing of their population.
Therefore, the people of Corded Ware:
-the presence of EEF genes
-pronounced horizontal profiling of the face in the upper part (more pronounced than in their Mesolithic ancestors)
-prevalence farmer-Middle Eastern mtDNa in all descendants of CW in Europe.
- burial form as "tower of silence" among the Iranians, has its roots in the Tripolye and possibly introduced by the Trypollian women in Indo-European culture (although, it could be just borrowing)
Also worth noting, from here probably there is an old confusion among paleoanthroologists, who indicates that people of CWC are often metrically similar to the Mediterranean.