He's a left-footed, left winger who I think occasionally plays deeper, like a left wing back and occasionally on the right as an inverted winger. As far as I know, he's never played right wing back for either Atleti or Belgium.
Always thought he was a very good player, haven't seen an awful lot this season. Personally, I can't see the point of signing an expensive (both in terms of fee and wages) older player and then play him wildly out of position.
That said, this is heat map from his last game vs Valencia...
The
Marca report said that he was poor on the right but was Atleti's key player when he moved to his proper position on the left.