Raul Sanllehi is critical of Arsenal for moving away from the management model he tried to introduce.
Sanllehi, now in charge of Real Zaragoza, says he wanted to ease the workload on the manager at Arsenal.
He told the Athletic: "Arsenal have betrayed the model I helped build. It is a mistake, but it is their mistake.
"In this model there are four points: head coach, sports director, operations manager and academy manager, and they must be well coordinated.
"I don't agree when clubs call their head coach a manager. Today the workload is overwhelming and you need the coach to concentrate on the first team.
"The head coach is oriented towards the short perspective – win the next game."