The attacking midfielder's struggle for form continued in the defeat to Bayern Munich and his compatriot believes he looks "lost" in Arsene Wenger's side
Ozil has been struggling to find his best form in recent weeks after initially impressing for the Gunners following his £42 million summer move from Real Madrid.
The attacking midfielder missed a crucial penalty in Wednesday's 2-0 Champions League defeat against Bayern Munich and was rounded on by Mathieu Flamini and Jack Wilshere in the second half for failing to track forward runs.
And Ballack fears his compatriot has not been completely accepted by the rest of Arsene Wenger's team.
"With his quality he should be untouchable and bring out so much in the team. But it looks like he does not have the acceptance of the team," he told Sky Sports.
"When he came to Arsenal there was so much expectation with the quality he has. The first games he looked good, played well and was comfortable.
"But now he looks a bit lost in this team."