It cannot move forward if the racket is pulled inwards. What you call away is just a trajectory which has forward and sideways components, and then a backward component well after impact. At impact, there is no backwards component. Away is not inwards. Away is to the left while still going forwards and upwards. The swiping is nothing but sidespin in some direction while the racket is still moving forwards. It has nothing to do with this. If the swipe is top to bottom and fast enough, the ball goes further than it would otherwise do (which may not be happening at all, as I said). Please don't mix separate topics together. A rigid body (the strings are not rigid but that doesn't matter here) cannot be pulling anything inward without itself moving inward. That occurs only after impact when the forward apex has been reached. No amount of jugglery can change this fact. You can make motions in the air and imagine that this can happen, but it cannot.