Under Pep he was great, at that time one of the best wingers in the world. Ancelotti arrived and did play Robbery instead. A simple explanation is that Douglas Costa did not have confidence of the coach, these things have an impact. Second argument he did not play all the time so hard to be in top form. Third thing, media said he wanted out almost all season. Maby he isent happy there.
IF Pep still was the coach, how would Douglas Costas season be? Would it be possible to buy him? Ask yourself these questions?