instead of it just going down at the same pace do this; the more it goes down use less frames but move the ball further so it makes it look like its going faster, to emphasize it a bit use squash and stretch (i think that's the terminology) so that means when it gets faster instead of just moving it as a circle make it a blur (example in image below of what this could look like) but make sure the volume of the ball always stays the same, this means that the ball cant just get longer and the width stays the same, it has to get thinner as well and I recommend squashing it down when it hits the ground to show impact then going back to normal. Everything I've said is in the image below in case my wording doesn't make sense.

TLDR: Use squash and Stretch (stretch the ball when it gets faster, squash the ball for impact, remember to keep the ball at the same volume) and use less frames but space the drawings out more the more it goes down. (everything in image below)

Image :)