Actually if you check
this article @Larrin states:
"The chart below has dotted lines which indicate the average effect of hardness for any given steel. So you can estimate how much a change in hardness would affect edge retention by following the slope of those lines."
Doesn't keen its 100% perfect but generally it's 15.8 TCC per point of hardness. The chart he references is below, the dotted lines are the" average effect" whereas the specific points are the actual data afaik (as measured in
this test) so you can see that no steel deviates much from that prediction.
I am curious though... If so much goes into testing hardness on a blade and its not as simple as we think, how can we trust these numbers or any knife maker for that matter?