Not a chance that Barkley suits the 8 role more than Kovacic. Kova is the better dribbler (Highest dribble % completed in laliga last season), better passer, better in one touch football (pass and move), better first touch and is not injury prone. Barkley is probably a better long range shooter but thats about it. Kovacic progress has been slowed at madrid, if he gets significant game time, he's on the same level as prime Rakitic.