@Ferrotter  
I respectfully disagree with your viewpoint. There’s a difference between a physical transformation and a chemical one.
 
Taking upon your butter analogy, if you let a lump of butter melt at ambient temperature, it is still butter, albeit in liquefied form.  
However, if you heat it up in a saucepan long enough to let the moisture evaporate, you’re left with butterfat, which isn’t the same thing as whole butter.

@Ereiam  
I would disagree. Even Sweetie Belle’s idea removed one of the tennis ball’s most essential components. The air inside is a structural element responsible for the ball’s ability to rebound. And she packed them in tightly enough to include only half the air of a single ball. Grinding them would remove even that. Burning is more extreme still, yes. But really, did you need the carbon chains of the latex any more than you needed the air? Are the ashes of 100 balls any more useless than the slashed halves of 5 or the particles of 20?
 
I would liken it to making cheese or butter. You can’t drink cheese or butter, but you still get the milk’s essential nutrition, in a package that allows you to transport many times over more milk for the same weight.

@Ferrotter  
But then, that would be cheating, as the whole balls wouldn’t be in there anymore (only their combustion residues), while blending a tennis ball keeps the ball whole, even if not together anymore.

@Ereiam  
If you burn them you can probably fit in the ashes of over 100.

And you can fit up to 20 balls if you shred them in a blender!

Sweetie Belle you so dumb