Former Arsenal defender Lee Dixon believes the Gunners' current defensive problems could leave them struggling to make the Premier League's top eight.
Arsenal boss Arsene Wenger accepted after a 2-1 defeat by Tottenham on Sunday that the title was out of reach and they would focus on the top four.
But Dixon said: "I think top four is out of their reach now, I really do, so you are looking at top six.
"Yet the way they are playing now, can they reach the top eight?"
Arsenal's struggles in defence were compounded after the game when the club learned that right-back Bacary Sagna would be out for three months after breaking his leg following a collision with Benoit Assou-Ekotto.
The Gunners' defeat at Spurs was their fourth of the season - and leaves them 15th in the Premier League table.
But Arsenal owner Stan Kroenke recently moved to reassure an under-pressure Wenger, by saying the Frenchman is the only person who will decide if he leaves his position.
Goals by Rafael van der Vaart and Kyle Walker earned Tottenham victory at White Hart Lane and Dixon believes the strikes were indicative of Arsenal's fragility.
"It is difficult for them because they are not showing any consistency in performances," he added.
"There are a lot of pluses and it's not all doom and gloom but ultimately it all falls back to the same thing. They are frail and they can concede goals from schoolboy errors.
"Until they stop that they will carry on being frail and that's the worrying sign."
On the performance against Spurs, Dixon added: "It is getting embarrassing. Arsenal get themselves into positions where they are the better team in midfield for big chunks of the game but defend like schoolboys by giving two goals away and numerous other chances that can be avoided.
"The second goal was a great strike by Walker, and the keeper was beaten by the swerve of the ball, but it came from a throw-in where there was no danger whatsoever and they just let Sandro run into the box without anybody getting within five yards of him.
"You can pick the positives out of the midfield which was a lot more coherent than Spurs at times, and Francis Coquelin played well, but it's all wasted.
"They can complain about the handball for Van der Vaart's goal but it could have been avoided 30 seconds before with basic defending."