If you go to your roster, you will see your fighters listed by rank by default.
If you have a few 0-0 fighters, their rank will be 0, but you will see they are not necessarily listed in the order you recruited them, and they are not listed by fighter id order, and they are not listed in alphabetical order.
So there's something else ordering them. And as I train them, they change orders.
And it's not by sparring sessions either. Just something interesting that I may never have the answer to.
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With each sunrise, you have a new chance, and with each sunset, you blew it. ~Jack Handy