Unai Emery has overseen a significant overhaul of his Aston Villa midfield this summer, preparing the club for Champions League football. In the middle, Villa have welcomed three new faces: Amadou Onana, Enzo Barrenechea and Ross Barkley. Onana is the most significant of those arrivals, a player who has long been linked with a club in Europe’s top competition. Although it helped their PSR conundrum, Villa will have been loath to lose Douglas Luiz, who was crucial to their success last term. Onana is a different style of player, and one that can still improve considerably through Emery’s coachi…