Former Everton manager Ronald Koeman has admitted that he is "disappointed" with how his summer signing Davy Klaassen has fared at the club.

The Dutch midfielder is currently out of the picture at Goodison Park due to his failure to adapt to the demands of the English game.

Koeman, who was sacked by Everton in October, has insisted that Klaassen's work rate cannot be faulted but concedes that the Premier League may have been too much of a step up for the former Ajax man.

"He had a difficult start at Everton, that was disappointing," Koeman told Ziggo Sport. "But you can not say that he does not train hard and works hard.

"You do not get time on the midfield. I was disappointed with Davy.

"I really expected him to adapt more easily. That's why I had also met him. Nobody in the club had doubts about him. Not in the Netherlands either.

"Klaassen was someone we spent a lot of money for and who could have really played a role in the midfield. In retrospect, you may have to doubt whether the step was not too big."

Koeman has taken charge of the Dutch national team since his Everton sacking.