Here is a term that has mixed meaning depending on where you utter it. At the acting/entertainment end of things you have the Man-soaps of the WWF. In Japan where athleticism is respected more that big muscles the Pro's know a lot more about real wrestling and as it shows a lot less about acting but hey that's what pays. Then you have the socalled "amatures who wrestle for the varios Olympic teams. Some are true to the term most are professional athletes whose dicipline is wrestling. All are students of the Human Body and much more so that most "Martial Artist" That a professional wrestler beat a Gracie is like saying a Bicycle messenger has beaten a Tour de France cyclist (this has happened a lot in small races here in the US).
As for a boxing ring being forgiving have you ever set foot in one??? I have it ain't nothing but a thin layer of foam over plywood covered by canvas. The bounce comes from the amount of undersupport the ring platform has. less for wrestlers more for boxers. Still its a hard surface. What you see when the wrestlers land is great ukemi. I didn't really understand it until I started training as a small Judo club that uses a simple wrestling mat over concrete. Good Ukemi is all that keeps us from pain but we see very little in the way of injuries.
And lastly what the hell does Parkinson's disease which is a genetic disorder have to do with professional fighting. Even counting Ali which if it isn't genetic then it is Parkinsonia and not related in any way. MMA fighting has none of Boxing's punch drunk symptoms/problems. The, relatively unprotected, hand strikes don't happen near as often in MMA as the punches do in boxing. Why cause it hurt's like hell that's why and because fights are called faster in MMA than in Boxing. Repeated micro damage is common in boxing, most MMA losers tend to lose fast they progress from at a slight disadvantage to helpless much faster due to the added tools (other than just punching) that a MMA person has.