The Russian, who arrived at the Emirates last January for a reported £15 million, is also concerned that the Londoners have lacked the cutting edge required to see off the top sides.
Speaking to Sky Sports, the 28-year-old said: "The fact that we have lost against our direct rivals this season signifies that we are not very good."
“We are not good on set-pieces because we don't have many tall players - every other team has an advantage over us in this area.
"They were much stronger than us when it came to physical power. Had we possessed a tall player then things would have been better for us”
"We had nobody capable of holding on to the ball. We played good football against all these top teams but that is not enough.”
The Gunners have suffered back-to-back 3-0 losses against sides currently in the Premier League’s top five – at home to table-topping Chelsea in the Premier League last Sunday, and at fifth placed Manchester City in the League Cup on Wednesday.
Earlier in the campaign the Gunners also suffered back-to-back league defeats away to Manchester United and Manchester City, but Arshavin has confirmed the squad are fully behind their manager.
"What we can change, only Arsene Wenger knows. He has been at the club for 13 years and knows the problems better than anyone. All the Arsenal players believe in him - and if he leaves they will all leave," the Russian added.
However Arshavin did hint that he felt Wenger should bring in another striker in the January transfer window, saying:
"It would be good if the club could sign some great players. It is up to the manager to decide whether he will sign a new striker in January. I have my own ideas but I won't say what they are.”
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