The January arrival from Freiburg has been a revelation.
Pardew said: "When we looked at the tape of him he wanted to score goals. There was nothing else you could see.
"But where he has improved is in his link-up play and his intelligence for where he should be on the pitch.
"I thought maybe we were buying just a goalscorer who might have been a bit selfish but I have not found that. He has a really good work ethic."