The Bosnia international scored 22 goals as Wolfsburg won the 2008-09 Bundesliga title and, while he has found it harder to net in the Premier League, Jol knows he has the class to succeed.
"I can remember Wolfsburg being champions and it was because of him," he said. "He was the top scorer in Germany and that is not easy.
"But he played with quite a few good players up front if you compare Wolfsburg then with the team now. It is a big difference.
"They had Grafite, for example, who was a very good player. They had [Zvjezdan] Misimovic, they played in a certain system - the golden triangle with Dzeko.
"I think it is only a matter of time. If you play Dzeko every week then you will see he is a quality player.
"But of course you have got [Carlos] Tevez, [Sergio] Aguero, [Mario] Balotelli so they've got world-class players."