I remember an interview with Baines last season (cba finding it) in which he was talking about how we tried to start last season by going all out to put goals past teams and one of the things he mentioned was playing with two out and out wingers (McGeady and Mirallas at the time) and how it backfired. Clearly it's something that's stuck in collective thinking of the squad, not just the manager. After say November-ish of last year, we've only ever played 2 wingers when injuries or suspensions have demanded it.
People seem to forget that for pretty much most of 13/14 we also never played with 2 wingers, it was mostly Pienaar or Osman with the other wingers being used as impact subs.