Ramsey will become one of the highest-paid players in the world when he moves to Turin this summer, with Arsenal having failed to tie him down to a new deal or get a transfer fee for the Welshman.
Crouch, who joined Burnley from Stoke in January, believes the Gunners have made another costly blunder in the market and is baffled by their continued mistakes.
Writing in his Daily Mail column, the beanpole forward said: “It has been a good week for Arsenal with big wins over Manchester United and Rennes but it's another week that has shown the error of their ways.
“I have written a couple of times this season about Aaron Ramsey and you will know my position – I found it madness they were not prepared to offer him another deal and I can't believe they are losing him to Juventus for free. Ramsey is quality.
"He is the type of footballer that should cost someone £40 million in a transfer fee alone. If Arsenal want to replace him like-for-like, that is the type of investment they will need to make, along with top-end wages.
"They will find it is no straightforward task. It's brilliant for him that he's getting the chance to play for a club like Juventus. Good luck to him. I hope he's a huge success and believe he will be.
“But for Arsenal to make the same mistake so soon after losing Alexis Sanchez has left me scratching my head. It was avoidable.”
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