Both I think.
The second half of last season played to his strengths - getting the ball forward as quickly as possible to him, stretching defences, forcing defenders into errors - the space he created also helped Tadic and Mane create chances for him. He was also on possibly the best hot streak of his career and the confidence was flowing, hence scoring goals like Newcastle at home last season.
This year I don't think we play to his strengths - our forward / build up play is a lot more technical and 'patient' which I don't think suits him at all. You can also see he seems completely devoid of any confidence - it's like he's concerned he'll only get one chance and must take it, whereas last year he knew he'd likely get several in a game.
Still a valuable asset for us, but probably wont see the best of him unless we change out style, which aint going to happen.