Ah, yeah. The whole "he played well as winger for Argentina/Real" debate. The difference, and a massive one, is the fact that he had players like Ronaldo, Bale, Benzema, Ozil, Messi, Aguero constantly pulling defenders away and making room for a decent to good winger.
Last season, when at his best, everyone else was really, really poor, hence why he stood out like a sore thumb, in the first few weeks. Unfortunately for him, when others found form, he lost his and found himself on the bench.
He reminds me of Rooney and his current predicament. Wayne's not so bad as a support striker or a wide forward, as he's shown over the years. However, if you place him upfront with the right players around him, he's a completely different player.