Well, I can tell you one thing statistically. If I take all the games he played as a pure right winger (not wing back), and all those that he was played on the left, the results are this:
RW/RM
42 Apps
8 Goals
8 Assists
LW/LM
13 Apps
7 goals
3 assists
That tells me that when has played, mostly for Fiorentina in 2013/2014, he did very well on the left side.
For example, he had one clear cut chance last game, but had to shoot with his right foot from the right side and it went wide. If he was on the left side, the chances of him burying that would have been much higher.