Change spacing of the ball between the frames to show ball's acceleration. Also, your ball is moving in a straight line, but it should have parabolic trajectory due to gravity. Ball should be fastest when falling down and hitting the floor, and slowest on top of an arc. You could also show sudden deceleration when aliens start stealing it to show ball's weight or the intensity of the aliens' tractor beam / suction tube.

A visual explanation of frame spacing for acceleration (i hope it turns out good when i post the comment).

Top of arc.............................Impact..................... ........Top of arc.
o.o..o.....o.......o..........o..............o..............o..........o........o.....o..o.o

I tried to show the ball kind of rocking forward then back in the beam to show sudden decceleration but I can exaggerate those effects in the future.

Thank you for the advice on the ball trajectory as well!! I'm still learning ^^;;

I noticed the bobbing. It was a nice touch. Good luck, and I am glad this helped a bit.