What's a book?

i get your analogy, only difference is the adventure goes on without you if you close this book.

Personally, I feel the game does a lot of quick statistical comparisons with modifiers (bonuses, attendance, SAs, OOP, and so on.
I still don't understand how formation/orders figure into it but it is definitely a deciding factor. I'd attribute the formation/orders matchup as being between 25-50% weight of the overall match calculation.