Was reading an article earlier today (I don't remember where), that suggested Xhaka was signed as a result of his rating on a new metric that originated in the BL that measures how many players are by-passed per game via passing.
Point being that this ability does not automatically translate to the player being a creative playmaker or suited to playing as the deepest CM.
IIRC there were reports last season that Xhaka had the most number of passes into the opposition defensive 3rd or something like that, whereas this year he's well down in terms of both Through Balls and Key Passes.
By all means play Xhaka in midfield, but NOT as the deepest CM.