You're kind of mixing up the 2 methods... For normal cleaning to get the dirt and silicone off, use the washer with jeans or towels and put them in a sock or mesh bag and let air dry.
As for roughing them up... when they refer to tumbling, they are putting them in an old dryer used only for this purpose (usually buy a used, small, cheap gas dryer with gas not hooked up)... the dryer is completely lined with sandpaper (60-100 grit) attached/glued to the inside. As the dryer runs, the balls will drop onto the sandpaper and scuff the balls, bringing the fuzz back. You can only do this a limited number of times as the balls will get smaller and lose their roundness. You have to consider if it's worth the one time expense and effort of doing this? If you were a vendor, I would definitely do it, but for an individual it's your call.