Frankfurt defender Maik Franz was in the spotlight after Friday night's 1-1 draw with Werder Bremen in the Bundesliga.
It followed a clash between Franz and Denni Avdic in the sixth minute which saw both players shown a yellow card.
"It's always the same," complained Franz. "Referees give me a yellow card for the first action I am involved in.
"They say: 'I'll show him a yellow card now and then he will calm down'.
"I have been shown 12 or 13 yellow cards already, yet I would say I am in the bottom half of the table when it comes to fouls committed."
Schaaf, though, claimed it is not the number of fouls Franz commits which make him so disliked, but the gravity of his interventions.
"We are always doing campaigns for fair play and then this player just puts his big boot in," he told Sky.
"There was a time when he was constantly being criticised. I would recommend that he changes his ways.
"The fans want to see tackles which are hard and with full commitment, but they should be fair."
Daum took Franz's side, though, and claims there is a "witch hunt" against him.
"It is unbearable," he said. "The Bremen players were always getting at him and wanted to provoke him all the time.
"When I see all that is going on then I have got to take my hat off to him for staying so calm.
"He is a faultless professional. He has had scenes in the past, some of them in the time under me, but he has always behaved flawlessly.
"He is fouled more than he fouls himself."
The game ended 1-1 with Bremen's goalkeeper Tim Wiese three times denying Theofanis Gekas in one-on-one situations as Bremen were lucky to get away with a point, despite leading until seven minutes from time.
"Games are decided by goals, not chances, and that is why I am unhappy," said Daum.
"We have lost two points. I am disappointed that we did not win three."