Pablo Piatti from the Spanish league is good for me in my Napoli save, but I'm not too sure how good he'd be for an EPL side... check him out though. He plays naturally as an AMC but even better on the wing.
Douglas Costa got young player of the year for me in my first Arsenal season (But on the right)he has faded abit in my second season though (In march of the second season at the moment! ) but that is probably because I used a completely different tactic for the first half of this season, and now I am using him as a winger again he won player of the month!
But Gervinho was my top scorer on the left wing as an inside forward, so you could probably be fine with him, with Walcott and the Ox on the right!
Also, Podolski is fantastic as an inside-forward on the left
2nd that. I play with inside forwards but if your looking for an actual left winger than consider going for Griezmann, assist machine from my own experience. He starts with a £21m release clause if you can afford him.