The France international came off the bench to score in Arsenal's penalty shoot-out win over Wigan Athletic at Wembley and then produced a moment of technical brilliance to find the net against West Ham United on Tuesday.
"He has done well," said the manager. "He has gone, like Mesut Ozil, through a more difficult period recently. It was a bit physical and mental as well with what happened to him.
"He is a strong lad, strong mentality, a strong, positive guy. He has a great mentality and that’s what I think got him back. He has scored 20 goals, that is a great record, and he is working very hard for the team.
"The quality of the goal [against West Ham] gives him, I think, confidence again. It gives him credibility again for people who questioned his ability, so that is important."
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