Valverde has alot of frustrations for fans, but if you watch De Jong's game, there is nothing about it that will cause Valverde to refuse to integrate him. Great first touch (unlike Malcom), tactical discipline (unlike Mina), strong on the ball, quick, great distribution. If you look at a player Valverde used in the past in Javi Martinez, that would probably be his closest fit, and Valverde made a really great version out of him. It is everything anyone would want in a midfielder.
As for position at Barcelona, I think if we played him at central midfield he would be making the forward playing passes with ease, much like how Arthur is doing it (and I did not see that in the 5 or so Gremio games I watched of him). With his pace and work ethic, he really could be the long term Rakitic replacement rather than Busquets. Reason being that his bursting runs from DMC are fabulous, but I can only suspect that that aspect of his game would be limited and contrived in our system.