Kroupi scored with a long range strike in the 2-0 victory.
"He's an accomplished finisher already," Murphy told BBC Sport after Sunday's win. "He has just come in and it seems like he already knows what his role is in the team.
"He is good without the ball, good on the press and works hard - but when Bournemouth attack, he gets himself in good areas.
"Bournemouth have got a lot of players who, even with the ones they have sold, are becoming real stars in the Premier League. Their recruitment is just phenomenal."
Meanwhile, Bournemouth boss Andoni Iraola said of the French youngster: "Junior is a finisher.
"His strength is that he smells the opportunities. His finishing is very good with his right foot and left foot. He has to add more to his game. He's coming to the Premier league and we still want more things.
"But if he helps us with goals like this it's always very welcome."