The young midfielder has established himself in Wenger's plans after a series of impressive performances, most recently against Norwich in the Premier League when he stepped off the bench to help turn the game in Arsenal's favour.
"Alex has made huge improvements. He is a very young boy at that level, but what he is doing already is fantastic and he has a part to play in our run-in," Wenger said.
"He has moved forward a lot this season. Since January, he has grown up a lot and you see there is more purpose in his game.
"You see it now when he comes on, he has a different stature and he wants to really take responsibility when he comes on which was not always the case.
"The final ball is much better and his concentration is at a higher level. That is what you learn when you go from a young talented boy to a real performing player."
Arsenal will be bidding for a ninth win in 12 league matches when they visit Fulham on Saturday, a run which started following the damaging defeat to fierce rivals Tottenham on 3 March.
"We bounced back from a very, very difficult position but we still have a lot of work to do," added Wenger, who has been forced to recall Wojciech Szczesny in goal after Lukasz Fabianski suffered a cracked rib.
"After the Tottenham game, we had no room to drop points and that is where we are. We know for us it is what is needed to be successful."