What sparked this train of thought was that I've just bought a team from eBay and it came with two balls mounted on 25mm bases. They look great and I haven't tried playing with them yet but I imagine the bases would make it a little tricky.
In the few games I've played up until now I've used the "spikey" ball that came with my box set as it stays on the base of the ball carrier a little better than the "non-spikey" ball with the grass surround.
And while my ball-related curiosity is idling away, how do you represent the ball being carried? Place it in the same square as the ball carrier? Place it on the ball-carrier? Does this wear off the base gravel/grass? Am I thinking about this waaaay too much?

Cheers