First when you make a fighter, you should check the learning speed. My opinion is that under 5.5 is too slow to be competitive at ID level and also too slow to wait for him to develop for top level with the skill cap going down with age.
After I get a decent learning speed, I like to test the fighter in the next 1-2 weeks in a test fight. Considering the hiddens TOTT hierarchy, I am keeping just Granite chin, good/solid chin and all the variations of KO power - KO power itself, Heavy handed and Big right hand. If it shows anything different, it means that ko power/chin hiddens are below the level needed to show on TOTT.