I think there's a few problems with his game right now that he needs to work on, some of which he showed improvement with last night so well done to him.
1. Too predictable when it comes to cutting inside to shoot. He has great teammates he can set up so a cross or pass is just as likely to be dangerous as a shot, despite his fantastic finishing ability. And most importantly it will keep the defenders guessing instead of always knowing where he's trying to go. If you're two footed then unpredictability should be your best friend as a forward.
2. Defensive impact. He works pretty hard but he's too easy for opponents to pass round, hardly ever gets a good foot in. He's probably even more ineffectual than Mata at this.
3. Partly related to point 1, but he needs to try to link with his full back more. You might not rate the full back you're playing with that highly, but if he's in good space and you've got the best header of the ball in the world in the box, you have to trust him to try to get a ball in sometimes. If you don't, you remain predictable and also damage your teammate's confidence.
I'd actually be quite happy to see him play on the left sometimes, as it will force him to mix up his game more.