Could the vain pursuit of ‘dream’ signings such as Vinícius Júnior at the expense of all-round strengthening come to haunt the champions? When Mikel Arteta revealed before Arsenal’s win at Aston Villa that he had pleaded with the Premier League to introduce bigger matchday squads, the final 24 hours of the transfer window was not quite what he would have had in mind. A deadline day on which Manchester City matched the British record to sign Enzo Fernández from Chelsea for £125m came and went as…