Have to say I haven't really understood if and how the NPCs' stats are important for counts or dukes. Do stats matter for your vassals? Or are they only important for yourself and for council members?
Presently, I am going by Four Commandments of Fiefdom that I learned from experience:
1. Never give out titles to Ambitious people, ever. Also, try to avoid giving titles to Envious people. Prefer Content vasalls.
2. Never give titles to close relatives, such as brothers, they will only ever stab your back when you aren't looking. As your sons grow up, only give them the bare minimum; no more than one county directly and no more than a two-county duchy with one vasall count transferred to them.
3. Never give out titles to foreigners, even if they seem nice. The -10 to -20 penalty _never_ goes away, and if his successor happens to be ambitious, you will never be able to keep them in line.
4. Thou shalt not give out titles to those who show too much Ambition. Verily, this commandment is like unto the first, but it is of such importance that it bore mentioning twice. (No rule without exception: sometimes I deliberately plant Ambitious counts into a duchy whose duke I don't like and/or want to keep busy. I always feel as if I'm tossing a rattlesnake when I do that.)
I have a feeling that numerical stats are mostly unimportant for rulers; except sometimes I give a fief to someone who would make a great councillor for me, but is currently employed in someone else's council. Giving them a title will free them up for you.
Apart from that, I look at the Virtue-to-Sin ratio and pick candidates that have as many good traits in common with me (for bonuses such as "Both Kind").
What do you say, are the numerical stats important for your counts?