This is a regular source of frustration among fans of clubs just outside the A-list. Why, when a player leaves their team for another slightly higher up the ladder, does an international call-up suddenly come their way? That may have been a question on the minds of many an Aberdeen supporter this week, when it emerged that Scotland boss Steve Clarke had included Connor Barron in his squad for September’s Nations League fixtures. While the most impressive of Rangers’ many summer signings so far, Barron is not really doing anything under an impressed Philippe Clement that he was not already doin…