Kanter isn't that great out of the PNR.
Four years sample size > 2 games
And yes by every person on earth's account he's been fantastic this year, but those games in January count as much as the games in February. It's the reason why he's not close to Harden Curry or AD.
As you said, Kanter has never played with anyone even closely resembling RW. The PnR opportunities are going to be there.
But this is a great case in point here of what we are discussing with anlaytics. Yes, Kanter has not been a good PnR player so far in his career. Is that his fault or the fault of the PG and systems he has played in?