IMO, it's a save that you only see the best keepers make, the best keeprs are the ones who use their whole body to stop the ball, hands,feet, head anything. Where as a keepr might try to get down to it, Harper just used his foot.
What?
You asked what is a world class save. I said it's the type of save you only see a top goalkeeper make...
Nah, the bit about a poorer keeper only blocking shots with his hands or something. Makes no sense, man.