How is this even something to debate?
You don't remember some of Gordie's line mates? Even Bobby Orr played with some average D-partners. I can even think of players who are worse than Kassian who lined up with McDavid in the past few years.
We are talking about the greatest players of all-time. Howe, Gretz, Mario, Orr, etc..
Another point is that even though Kassian was on McDavids line at the beginning of games, he rarely played every shift with McDavid. Most of the time Connor ended up with different line mates by the end of the game.
