You gotta source your stats dude. I'm not going to believe any figure anybody just pulls out of their ass.
He has no source because he's wrong. The win rate of a fighter taking a fight on short notice is exactly 50% because no matter what if 1 fighter agrees to a fight on short notice then the other fighter is also agreeing to the fight on short notice.
Now obviously he is talking about a replacement fighter coming in that didn't have a camp vs a fighter who was already on the card. If fighters are taking fights without a proper camp and they aren't in shape 100% of the time like someone such as GSP then they probably deserve to lose.