The Jorginho-Kovacic midfield gets bypassed way too easily. It's no surprise he wanted to have Kanté back as soon as possible. That midfield partnership along with Kepa was the main reason we conceded so many goals. The team had no idea how to play off the ball as soon as teams got through our press(again thanks to the huge gaps in midfield).
I don't see how Kante being integrated back into the team after returning from injury buggered up our momentum. If anything, we were desperate to have him back in the starting line-up. As to wether he is less fit to play in Frank's system than the other midfielders. He has proven that he could play anywhere. He was made to play higher under Sarri and Lamps because his talents would be wasted playing deeper as he is now, but also to accommodate Jorginho who can only play the one position.