Maybe not underappreciated, I feel he has just had his struggles at the different clubs he's been, especially with injuries. Perhaps, his time at PSG has been the most fortunate for him.

When he first joined Manchester United, he showed glimpses of the star he could become, but he fizzled out, coupled with the pace of the game, expectations and injuries again.

At PSG, he has been a bit stable even though injuries still haven't left him.

At country level ironically, he looked to have found a way to be regular and like you mentioned, especially at the Beijing Olympics.

A very good player on his day, no doubt, still, his talent isn't up there with the likes of Messi and Aguero.