Wilshere impressed in victory over West Bromwich Albion.
"Have we got our old Jack back? Yes our young old Jack," said Arsene Wenger.
"But he is not at his maximum yet, but on his showing against West Bromwich he is not too far away.
"He excites me, I played him when he was 16 because I saw something.
"I'm just happy that a boy of 20 can play football because he was out for 15 months. I believe the surprising thing for me is how advanced he is.
"I expected him to be back, next year in February, at his best. He looks much earlier than I expected him to be.
"But I still have to be cautious. For example, against West Brom is the first time I see him very very close to the player he is."