Ballack, a German team-mate of the playmaker, believes Ozil should have fought for longer at Real Madrid.
"For me in particular, I would have liked to see more time fighting in Madrid [from Ozil]," Ballack said in a Q&A with Marca.
"It was a shame, because I'm sure Cristiano Ronaldo and Benzema would have loved him to continue, because Ozil is a very generous player."
He continued: "His transfer from Madrid to Arsenal started fine, but then it has been hard to adapt, because English football is very complicated.
"Özil is one of our best players, a large number '10 ', but doesn't assume a lot of responsibility.
"He is a free player on the field, which has great influence on the game, with amazing quality, but sometimes his body language is not what it should be for a player of his class."
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