Well, I suppose I'd have to respectfully disagree with you then mate. I'm a big believer in the power of statistics in general as a tool, but it's important to keep in mind that stats in football are really in their infancy, particularly on the defensive side of the ball. I know it's very hand-wavey and a bit anecdotal, but Kante's impact goes beyond what we can currently measure. The security he brings to the midfield allows the rest of the team to play with so much freedom-for instance now Hazard doesn't have to defend and can roam the entire attacking third, destabilising the opposing defense. That's a direct result of Kante's presence, but how can it be properly quantified?
I will say that Herrera is absolutely underrated by the wider public, which is a bit of a shame. I don't think, however, that he could do the job of Kante in a 2 man midfield, but he's the perfect complementary player for Pogba as an energetic box to box midfielder in a 3 if you put a deep lying passer behind them and approximated the Juventus midfield of Pogba-Pirlo-Vidal.