Exasperated Charlie Nicholas has questioned Arsenal boss Mikel Arteta's use of Kieran Tierney.
The former Gunners star has demanded the Scotland international be given more game-time in order to get fully fit.
Tierney's Premier League start against Manchester City last week was the left-back's first since December and he was then benched for the weekend defeat to Brighton.
But Nicholas insists the ex- Celtic favourite needs minutes to build confidence - although questioned how he can be expected to operate in full flow in a ropey Arsenal defence.
"How do you work it out for Arsenal?", he told told Sky Sports.
"The defence is poor - Mikel Arteta left Kieran Tierney out, but he does need games to get fit.
"He needs games to get confidence, but how do you get that in this defence? He has been brought into this."
At the weekend, Nicholas revealed he believes the club should sell captain Pierre-Emerick Aubameyang in order to fund a rebuild - and says the bulk of it should be spent on the backline.
He added: "Take the money for Pierre-Emerick Aubameyang if the right amount comes in, and sell Granit Xhaka as well. There are 10 players Arsenal could sell.
"It goes into a fund to get more defenders. All the best teams in principle have the best structure and they resolve their defensive issues. Liverpool paid big money for Alisson and Virgil van Dijk, and they paid £8m for Andy Robertson, who has pace and quality.
"There is nothing to say that it will take years. The board and owners do not have years as the crowd will turn on them if they do not identify that the defence is everything.
"It is the area that matters right now. If they do not address it they will get further and further away from it. This is a must. Whoever you must sell, the funds must go on defenders, and you start building again."
