Zappa - No one is commenting on your lack of experience with chins as compared to the people who have had many years of experience who are commenting on your thread. We are simply telling you, from experience, chinchillas do not wrestle. Period. When kits wrestle? They rip each other's faces open, rip eyes out, and tear off ears.
When adults "wrestle" they jump on the other chins back and hold on until the other chin is down or mortally wounded. They skin them, like an Indian scalping in the wild west, from their eyebrows back. They puncture holes in their lungs. They tear strips of fur and skin off, exposing muscle and bone. The chin on the bottom doesn't stand a chance.
I wish I had taken pictures of a chin who is finally starting to heal now that just had this happen. He and his cagemates started chasing each other, much like you are describing, but I saw no fur fly, so I didn't panic. That night I went out to feed, 6 hours later, and he was a bloody mess. He was a white, so it showed up ever so much better. His ears are ripped to shreds, his back had stripes, like if you took all five of your fingernails on one hand, dug in, and ripped. His nose was ripped open, his cheek, the back of his head. I spent an entire weekend with him on my chest to keep him warm and out of shock, filling him up with antibiotics, pain meds, and all kinds of other fun stuff. I am actually amazed that he made it through. He wasn't the worst I've seen, but he was right up there. There were four little weanlings together, and one of them tore up the other three. The white was the worst of the bunch.
Chins do not wrestle when playing. If your chins are wrestling, just please be aware that this could turn bad really fast, and it almost always happens when you're not home and you can't step in to separate them.