animator :
Your question is a bit complex, because the solution depends on how you solve the ball.
Physical concept:
To make a ball drift in a curve, you need to hit it off-center (can be also angled). It gets a spin through that. The spin causes the sideways-offset, since the air flowing around the ball has different speeds (thus density) on each side, so like a plane takes off, the ball goes sideways, because of air pressure differences. The bigger the rotation, the stronger the curve. (If there is no wind and you hit the ball in the middle it will not spin much, and you shoot quite straight.)
So you could detect an offset of the hit from the center-point of the ball - the more offset, the more you let the ball fly sideways (You can also give it a rotation speed according to that, if you want realism.).
The only question is, how you let the ball fly? A behavior?