Ive tried this a couple times, just have trouble keeping the focused locked on such a moving object. Deff agree 3rd is the best, and looks decent. What's your shutter speed on these?
This is strictly a educated guess, since I have never tried panning myself, but I think one of the issues on all but the last one (which I really like, by the way) is there is too much movement in multiple axis. One of the things I remember reading about panning is you only want movement on one plane, and in one direction. And you don't want the subject moving toward or away from you. So either left or right, or up or down, and never toward or away.
Something for you to chew on, anyway.