If you've ever had a stinger, or a numbing pain after a hit or incident, you'll know that you can't feel a damn thing, and that you have no control over your limbs. You don't know if it's severe damage, or just a bruise. It's quite common after getting hit with a baseball or puck in an exposed area. When i was a young teen, I was playing around on a pile of big rocks on a construction site. Another guy who I was playing with disrupted a large rock which came tumbling down the hill, just missing my trunk, but hitting my leg a glancing blow, or so I thought. My leg went numb, and I hopped, one legged, down to the road, swearing at my friend, and wincing in a combination of pain and numbness. I thought it was another one of those minor hits that you get all the time when falling of a bike, or getting kicked in a soccer game, etc.. It wasn't until my friend came down and looked me, then at my leg, then back at me with a white face that I suspected it was other than that. Turns out I was rushed to the hospital and given 80 stitches for a leg that was opened to the bone along the length of my shin.
The point is that these guys aren't faking anything. They just don't know anything besides the fact that they can't feel, or have control of, the body part in question, and that's never a good thing.