Cain Velazquez could have been the best heavyweight of all time. Cain Velazquez should have been the greatest heavyweight off all time. When he had one professional fight, people knew this. The moment he stepped foot into the American Kickboxing Academy, the people there knew it. The people who some him train, even before he had his first fight, they knew it too. Everyone knew.
Jake Shields, one of the greatest and most unheralded fighters in history, as far as my extensive(cursory) research suggests, will become the first fighter in MMA history to have fought both a father and his son, when he steps in the PFL cage to Fight Ray Cooper III.