I saw Deelkens once in a full game at STVV. He played a good game. He denied STVV from some good scoring chances and made a good impression. In that game he was really good in corners. He is rather tall and because of that he mostly had the ball safely in his hands with most of the corners.
He was also very good in anticipating situations back then. He doesn't fears to come out of his goal and play behind his defence.
But like you said somtimes he is to quick with punching the ball wildly away but that's because he is still young and is afraid to make mistakes when trying to hold the ball in his hands..
Another young goalkeeper that impressed me is Davy Schollen from STVV. ALthough i don't believe he will ever make it as one of the best in Belgium he makes good saves and has some stunning reflexes from time to time.
Maybe if Brockhauser played more games at Genk i would have choosen him as the best goalie until now ..