I don't think it's a race thing (and PTR is trolling all of you anyway).
But I think it's a fancy-stats thing. Kane, despite his numbers, destroys the stats of the line he is on. Is it a chemistry thing? Is it just about the way he plays the game? I don't know, but I think GM's don't see him as "plug-n-play" like they might see other players (like Nash, who has played on a couple teams with success).
Kane, because of how he plays the game, is simply a bigger roll of the dice. If you have a line that isn't producing anyway then he probably wont do much damage. But you might be in trouble if you're trying to plug him into a line that already works just fine.