How exactly do the "Star" ratings work

[oaklandmurphy]

The rating of units in this game is a bit confusing, brigades with the same number of stars often seem to have dispirit levels of usefulness (this seems particularly prevalent in the Army of the Patomic). For example, Cutler's brigade seems to be almost on par with the iron brigade despite having only 2 stars, but Baxter's brigade and the bucktails seem much less effective even though they also have 2 stars, is there more going on under the hood than just the star rating? Do the 200-300 extra men that cutler has make that huge a difference? Or am I just imagining things?

 

Disclaimer, I have only really played as the Confederates for the most part. Am I just using baxter and the bucktails wrong? I try to keeps the enemy at arms length in a firefight and avoid melee, should I be more aggressive?

[Koro]

I suppose it can be a bit confusing but from how I understand it the stars are merely indicators of how strong a brigade will be. On top of that, the brigades have individual stats that make most of them unique. 

The Iron Brigade is a much stronger 3-star brigade than some of the 3 star CSA brigades f.x. and Cutler is much stronger than other 2-star brigades. The entire Union 1 corps as a whole is better than the other Union comparable stars too.