I like the idea, but I think I'd try it in the reverse. Maybe try having having the balls all bokehed out, and have the moving ball stock still.
Or better yet, keep it all in focus, with just a smidge of motion on the moving ball.
i like it.. except the one ball that's out of focus, i find it terribly distracting.. it looks more like a smudge on your lens than a tennis ball.. other than that nitpick i do like it!