For this version, the ball starts 1/3 of the arc from the top before the first drop. The top of the initial arc is 48 inches with a 1/2 second drop. Each bounce loses half of its' energy, using the first bounce as guide for the timing of the following curves. I added a second contact frame for each bounce like page 94 of "The Animator's Survival Kit". Here is an image showing the "Y" movement.
The "X" movement is an arc composed of linear segments:
The largest stretch for each bounce occurs on the first contact frame, then the largest squash on the second contact frame, the ball returns to the largest stretch on the frame immediately following the second contact frame and gradually changes to zero squetch at the top of the arc. The entire squetch channel is set to "Zero Slope".
Here's the entire ball bounce onion-skinned:
The shaded wireframe animation:
The final render:
