Perez has stepped up after Andoni Iraola's departure for Bournemouth and led Rayo impressively since taking charge.
Cobeno told Radio Marca: "The doubts were normal because he had no experience. We knew him very well internally, but externally I understand that it seemed risky because the sensations were not good. We thought that with the base already made and the presence of certain players that he demanded, the team would take a step forward."
Regarding his renewal, Cobeño is clear: "With Andoni Iraola we went year after year calmly. There is a very good relationship in every sense. He is very happy because he knows that it is a very good showcase, there is pressure here, but good because football is experienced in a different way.
"The renewal of Iñigo Pérez is a path that must be extended over time because it is good for everyone."