I think the experiance thing comes form the way you use your troops. I tend to spred the fight across my line so no one unit takes a big hit in casualtys. I don't know how the auto resolve dose it but it kills a lot of men and then makes it easyer to get them experiance. I have found regularly puting the same unit in the middle for the front line or out on the flanks if you are fighting a battle when you are out numberd well get them more experiance beacouse those are the places where the fight is usuealy the hardest. Basicaly put them in the middle of the bigest and toufest of their line and you will get you cheverons you want.