For the average fighter, that's pretty spot. However , there are alot of exceptions to the rule in this sport as far as damage, mileage ,fight IQ and then there are actually talented fighters that start late.
Also, ones prime / shelf life can get cut down quick on a devastating finish or it can go the other way if one knows how to defend himself.
OR- wrestling based fighters who 100% use their wrestling in every fight and win more than they lose.
This sport not as cogent/ clear as other sports but I agree on the average but the average in this sport holds a less percentage than other-
Also - across weight classes can provide different figures.