Martin Keown said that Shkodran Mustafi was defending Crystal Palace as a "schoolboy".
The Match of the Day expert says the 27-year-old should take responsibility for each of the Eagles' three goals, which casts doubt on Arsenal's four main hopes.
The 3-2 defeat could be damaging, but manager Unai Emery defended the central half after another calamity.
The fan and comedian of the gunners, Jack Whitehall, wants the player to be banned for two years.
Keown, meanwhile, eliminated every goal that pbaded through Arsenal and says there is no hiding place for the central of large amounts of money.
In the first game of Christian Benteke, he said: "Look, Mustafi is completely turned off, it's schoolboy things that he really is.
"Your work should be done on the training field, not during a game, it's too easy."
He went to the second of Wilf Zaha and said: "He has overcome the muscles, his bad decision-making is costing his team: key moment and individual errors.
"Then he stays there, he just comes back and defends!"
The eventual winner of the Palace could also have been avoided, believes Keown.
"Mustafi loses his man, but Arsenal must take possession at key moments like that," said the expert.
The 27-year-old failure was also criticized by the fans, but not by their manager.
But when asked about Mustafi's performance, Emery said: "They have very good players, secondly, we do not work and we are strong as we are doing all season."
"Generally we can talk to the players and they can play very well, sometimes they do not play with due diligence, but I prefer to talk about consistency throughout the season."
"All the players are helping and playing with great performances, but today, defending against Benteke and Zaha, you can suffer more."
"If today we were better on the set, maybe we could win this game, we also controlled possession but defended well, we did not find the best situation to score."
He felt pressured again by Mustafi and Emery said: "It has been consistent."
The fans want him to leave in the summer and one wrote: "This man could be the biggest loss of money in the history of the Premier League."
Another wrote: "Something more to thank Wenger!"