Originally Posted by toly
According to Rod Cross topspin formula:
1. If direction of the racquet velocity is above of the normal to the racquet string bed, then Djokovic hits topspin backhand.
2. If direction of the racquet velocity is below of the normal to the racquet string bed, then Djokovic hits backspin backhand.
This is the main factor that builds ballís spin. Closed or open racquet doesnít create topspin, but changes outgoing ballís trajectory (low or high arc).
Well, what would be the point of hitting a very hard low-to-high swing path, closed racket face shot?
The effect would be to create a very heavy topspin shot that goes low over the net so therefore cannot kick up to head-height on the opponent... One of the major advantages of heavy topspin is that it can be used to kick the ball up to above head-height on the opponent, thereby forcing a weak reply. You can hit so high and fast over the net that a spin-less moonball would fly miles long, but the spin will dip the ball in and force people to deal with this bounce. You cannot do this if you hit low over the net - even if you have heavy topspin on the shot, a low shot bounces low.
I suppose if you hit a heavy topspin shot low over the net you can hit harder and have the ball still dip in before it goes long, but isn't it easier to slow down the swing slightly slower, open the racket face slightly more, and hit more through the ball in a flatter swing path like Berdych and Tomic? They can swing slower because all of their racket-head energy goes into pace, not spin. Their shots will have just as much pace as a heavy topspin shot aimed low over the net.
It seems to me that you can either go for a high looping shot, in which case heavy topspin is your friend, or a flat kill shot, in which case topspin has little use.
What is the advantage of a low, heavy topspin shot? You can't exactly say it has high margin for error because it still goes low over the net. You can't exactly say it will cause a nightmare to deal with when it bounces, because it won't kick up to above head-height. I can't see an advantage of this type of shot - if you're hitting low, you may as well hit flat.