Hasenhuttl highlighted Ward-Prowse's new-found physical prowess as the reason for his transformation.
Saints' manager explained: “I think it was the biggest change in his game since I'm here.
“He was always a good player and had a fantastic right foot but never nobody saw him defending or winning balls like he does at the moment.
“This is maybe something he had to learn, and he had to show me, he did it.
“After a few weeks when I was here, I could see this transformation in his game was there and in the end, in modern football, every player has to have everything, also the strikers have to work against the ball, and the centre-backs or the full-backs must be a number 10 when they have the ball.
“This is in modern football necessary, you cannot have any weakness and Prowsey is on the way to getting a full package."