Having three very good defensive wingers in Nichushkin, Landeskog, and Lehkonen gives the Avs some leeway when it comes to center. Kadri was pretty good in all three zones last year, but most agree last year was a bit of an outlier where he absolutely blew his previous career totals out of the water. But before that, Kadri was no great shakes defensively, and while MacKinnon has made an effort to work harder in the defensive zone, he's by no means good in that end of the ice. Same thing with Rantanen.
IMO Rants will be tried at 2C but he won't stick there.