He told De Telegraaf: "Robin is an exceptional player and an exceptional person.
"I no longer work with him, but he will only have developed further. And the Robin who left me after so many years was already quite different from the Robin that I found in the second team of Feyenoord at the time. I have experienced the evolution and the revolution of the football player and man.
"We could talk about football or other matters for an eternity. I loved his honesty. He had the ability to analyze everything with his football brain. He went very deeply. He asked a lot of himself and his environment. He was always looking for the truth. How is it exactly, what is the best now?
"What I appreciate as a person in him is that he is not superficial.
"As a player, he trained and played football with me at an unprecedented intensity. I think he has not changed anything at Feyenoord. That intensity is also in 'being human'. When it comes to perfecting the group, the team on the field or team spirit, there is no room for jokes with him. He demands the utmost of everyone and dares to name everything."