with what kind of statistics u want to balance then? i see no alternatives, u need hard data and cant just say "hm this units feels stronk, this feels weak lulz"
ofc winrate is not everything, but its a keyfactor with popularity and winrates spread across the skill levels.
I don't want to go into detail and start a seminar regarding statistics becuse majority of it will be lost here and frankly not needed.
It is a rule of thumb however that you need very big sample to make your calculations accurate enough otherwise it's just lottery. A sample size of 100 is nothing not to mention that this sample can't be even compared as so called skill difers from player to player therefore 100 OKW players aren't equal to 100 Soviet players skill wise and so on. Even the popularity of a faction can affect the score as we observed with UKF launch.