They better not be, or Dana White would punk their asses for endangering the product. You honestly think they're getting into real MMA fights every week?
You do know it's like sparring EVERY DAY for like 6 weeks before a fight? Along with a run in the morning (Most do about 5 miles), then breakfast, followed by weight/power, followed by sparring or grappling, then a rest, then more cardio stuff. They do that every day. Oh and diet is alot more hardcore. You have to build weight, then lose it, then put it back on. Some guys like Anderson Silva go from 205lb (Lightheavy) to 185lb (Middleweight). So thats 20lb's and when you are just muscle, thats hard work.
If I wanted to fight, I'd have to go from 155lbs (Lightweight) to 145lbs (Featherweight) or even 135lb (Bantamweight).
Aswell, WWE guys live alot "unhealthier" lifestyles, some smoke, some drink. Where as, a full time MMA fighter will only drink when they don't have a fight coming up and smoking is out of the question completely.
PS. Normally when sparring you don't wanna go full throttle. You still need training partners, if you injure them all, who can you train with?