He said: "Perhaps I can understand if people are worried but you are not here every day to see the way we try to train, and the way we try to improve.
"We have new players and a new manager and it needs time to get used to each other and the things the manager wants. It will be better.
"When the manager came to Holland to try to sign me, he said he had seen me playing and he knew what kind of player I am.
"During my conversations with him, I recognised the same mentality so that was good for me.
"It was important because the mental effect is massive. In football the team is the most important thing, not the individual. When you are all focused you can go on the pitch with a feeling you are invincible.
"If I look back to Feyenoord last year, compared to the season before, there was a big difference in the players and the team in how we were together.
"We can really make big steps like that here too."