Arsenal evidently set out on a clear mission to improve Mikel Arteta’s squad depth this summer in order to bridge the small gap to Manchester City. The task was a relatively simple one: replace players on the periphery of Arteta’s squad with high-calibre alternatives. A simple plan in theory, but one that was always going to be difficult to execute in a slow transfer market. Perhaps Eddie Nketiah’s predicament is the best example right now. Nketiah has agreed terms with Marseille to leave Arsenal – a move that could kick-start Edu’s plans to bring a new attacker in before the end of August. Ho…