We can see the benefits of having clear numbers for military strength, but just when you think you know who will win without a doubt, it turns out the seemingly losing party has a John Rambo on their side who single-handedly eats a quarter of the other army for breakfast.

Essentially, numbers can give a good idea, but unless you're playing a computer game with locked stats, you can't be sure who will win even with the numbers. Much easier to flip a coin.