The midfield maestro featured in die mannschaft’s ill-fated World Cup campaign.
He’s since asked not to be selected after claiming he was being scapegoated because of his Turkish heritage.
Gunners legend Petit has criticised the former Real Madrid star’s motivation in an Arsenal shirt.
However, he concedes the furore in the summer must have caused issues.
He told Paddy Power: “We all know how beautiful a footballer Mesut Ozil is – when things are easy.
“It’s easy not to have to be physical when you are winning but it’s when things are not beautiful, when you have to fight, that you can lose him for 60 minutes.
“I think what happened with the national team has had a big impact on him in terms of motivation and it’s taken a couple of months to recover from that.
“I’m not surprised by Emery’s comments (about Ozil not able to handle the physical confrontation) because I have seen so many times how he disappears on the pitch when you need fighting spirit.
“If Arsenal want to reach the level they are going for then they need him to be at his best.”
The Gunners were accused of having a soft underbelly under Arsene Wenger.
Unai Emery’s arrival in north London appears to have improved Arsenal’s resilience though.
He snapped up Lucas Torreira and Matteo Guendouzi to add steel in the middle of the park.
Petit reckons Torreira’s arrival from Sampdoria has been a game changer.
“Torreira is like a dog,” he added.
“He’s everything Arsenal have been missing for the last few seasons.
“His work rate is very impressive, he’s very strong mentally.
“He’s not the most talented player but in terms of setting an example and fighting spirit, he’s a leader in the team now.
“Arsenal haven’t had a player in this mould for a long long time.
“They have Matteo Guendouzi but he’s young and will take some time to develop.
“Xhaka is also much better player with Torreira there.
“Torreira has made him a better player because Xhaka wasn’t like that before.
“Since he moved to Arsenal I hadn’t seen him improve as a player and now he looks like he has come on leaps and bounds.”