Here is a ball throwing animation which used Walker3D and a parabolic walk path. One walk cycle was made, then the path was parented to a prop which was rotated 180 and a second walk cycle was applied. The walk cycles only apply to the ball when in the air, When it is in the hand a diffrent ball parented to the hand is used, and the "flying ball" is translated below ground for those frames, likewise when the "flying ball" is in flight the other ball is below ground. Linear interpolation was used throughout the animation.