As the topic says, my problem is quite simple - I cannot find a rule (if there exists one) for adjusting CR to creatures, in my case Drow, with Player Classes (fighter, cleric, etc.
) but only average ability scores. The MM tells us, that "Drow with PC classess have their CR equal to class level +1". The thing is, PC classes come in one package with elite ability scores...and as I said, I want average scores. Can someone help me solve this problem, also please put your thoughts on the topic here !! 

