It's still probably a bit too soon to write him off but you expect him to at least do better against Sunderland.
I've got my own theory like.
His style is very ball shy, like all the time he was with Ajax and for the Netherlands he is not like a Davies, looking for the ball constantly.
Instead, he gets in like high-value positions, and when the game comes alive so does he. He's come from a whole life of playing with Ajax in which every player is probably super comfortable playing one and two touch stuff in quick succession.
When the ball goes near him he uses it well, and he doesn't often make poor decisions, but he is never going to get on the ball for the whole game or dictate the pace of it. Hopefully his goals and assists start to rack up because that's the cornerstone of his career - timing of runs and clever finishes, if he can do what he does ATM but match his previous output we'll all be very happy...but one without the other is some danger of looking like a luxury.