Magath and Holtby also worked together in the past at Bundesliga side Schalke.
"Lewis is a very skilful and a nice player but he is not a fighter - I think it was not the right move for him," Magath said.
"I think he has put too much pressure on himself.
"Against Hull it was not him who was playing and against Stoke it was even worse.
"It was too early, he came here for a chance to go to the World Cup but after a few weeks it was clear it wasn't working. It was not the right decision for him."
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