The former midfielder admits he is growing annoyed at the number of injuries the side are suffering.
The Gunners have a growing injury list already this season, having lost several big players in recent weeks.
They lost Aaron Ramsey to a hamstring injury in the 2-0 win over Bayern Munich on 17 October, before losing both Alex Oxlade Chamberlain and Theo Walcott to similar injuries in the defeat to Sheffield Wednesday.
Defender Hector Bellerin then joined them in the treatment room as he pulled out of Wednesday’s Champions League game with Bayern, while Laurent Koscielny also sat out the game injured.
And Petit says big injuries such as these are what annoys him about his old side, saying they have cost them many points over the years.
“To be honest with you, I’m getting very annoyed with that,” he told BT Sport.
“They have a problem with injured players, it costs them crucial points and crucial games all the time. They have a very good squad, but injured players cost them many, many things every year.”
Given that the Gunners were beaten 5-1 at the Allianz with so many key players out injured, it is easy to see where Petit is coming from.
Hector Bellerin in particular was a big miss after impressing in the first game, with Mathieu Debuchy noticeably struggling all game, while Gabriel looked like a poor replacement for Koscielny in the heart of the defence.
Now they will have to hope that the injuries don’t have a negative effect on their Premier League form, with Tottenham up next in a big London derby.