The Dutch international midfielder rejoined the club from Tottenham Hotspur last summer, but has been criticised for his lack of dynamism.
"I think people have to be careful with statements that there's no place for players like him in modern football," Fink told Goal.com. "Van der Vaart scored five goals and created 10 more last season.
"For me, he is still one of the best players around in the Bundesliga, just like before. He has the ability to dictate the tempo of the game, is very dangerous in front of goal and is a real leader.
"That's why I think it's a bit of a joke to say he doesn't fit in in modern football."
Hamburg finished seventh in the league last season.