Unit Values - the Theory

[Bangla]

Apologies if this has already been discussed, but I couldn't find anywhere any Designer's Notes or articles about the theory of the game design. Particularly when it comes to the different values attributed to comparable units from different nationalities.
I'm assuming not only weaponry, but training, morale and doctrine also play a factor, but I can't understand why, for example, Russian Infantry in EFD are 4-2 and remain 4-2 and inferior to German infantry in Kursk.

If anyone could point me in the right direction to get info on unit value design, I'd appreciate it.