By Grey Whitebloom As Xavi Hernandez signed off his glittering playing career at Barcelona with a second European treble in 2015, he had a message for the tearful crowd: “I hope this isn’t a goodbye but a ‘see you soon’.” Xavi’s shock announcement that he would be stepping down as Barcelona manager at the end of the season carried a sense of relief, from all parties involved, that screamed good riddance rather than goodbye. Hours earlier, the Catalan giants had slumped to an extraordinary 5-3 defeat at home to relegation-threatened Villarreal. After overturning a two-goal deficit to lead 3-2, …