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" and cheated the height lower on the last four bounces to get a lower final bounce. 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 about 60% of the distance from the ground. The entire squetch channel is set to "Zero Slope".
The "pivot" bone is in the center of the ball ("0" on the Timeline) except for the contact frames...it is at the bottom of the ball for those ("-100" on the Timeline):
Then, I manually aimed the "pivot" bone at the center of where the ball will be on the next frame using Onion Skinning. Here is the entire bounce with the "pivot" bone visible as a blue line:
Here's the entire ball bounce onion-skinned in shaded mode:
I then added some roll using the "geometry" bone:
The shaded wireframe animation with visible stripe:
The final render:
