The Genetic Origin of the Indo-Europeans

[Jaska]

Yamnaya literally means "Pit Grave". If this type of burial was not distinctive to them, they would not use that name.

No, the logic does not go like that. Naming the culture also depends on in which order cultures have been found and named and how well they were known at the time. The Yamnaya grave developed from earlier grave types, the pit and the mound being present already in the Samara Culture:

"The graves found are shallow pits for single individuals, but two or three individuals might be placed there. Some of the graves are covered with a stone cairn or a low earthen mound, the very first predecessor of the kurgan."
https://en.wikipedia.org/wiki/Samara_culture

Yes, the logic goes exactly like that. Cultures are named so for a certain reason. Corded Ware is named Corded Ware because they found Corded Ware.

Perhaps I misinterpreted your use of the word "distinctive"? I thought you meant exclusively. 
So, naturally there are corded ware pots within the Corded Ware cultures, and there are pit graves in the Yamnaya = Pit Grave Culture, but corded ware ceramic is not restricted into the Corded Ware cultures, and the pit graves are not restricted into the Yamnaya Culture.