Was there ever a position when one would have been mandatory to the other?
I'm assuming that the rules would have still applied. ie not taking the fight would have resulted in one of them being stripped of their position.
But how else are you forcing two guys to fight? You can't. And I respect that they wouldn't have fought.
When you become a champion of one of the alphabets, the others tend to remove you from their rankings. Even pursuing a high ranking for the WBC for example could have you removed or moved down on another.
The brother who won would've elevated his already great legacy, while the brother that lost would slip down the ATG. It would've been awkward for the rest of their lives.
Their mother was the reason they never fought, they asked her several times and she always told them no.
Comment