I could see his right foot was very swollen right after he threw his first let kick. Goldy even mentioned that he hit KZ with his foot. Unfortunately for Aldo that was the first and only kick he threw in the fight, well I think he threw two but after the second kick realized he had injured himself.
This is why he wrestled and stalled the fight, he was fighting with a possible broken foot. It had a serious impact on the fight, limiting his movement, power of his punches, and effectively taking away his biggest weapon.
Yet he showed the heart of a true champ, not once complaining to his corner or visibly showing he was in trouble. That's what champs are made of folks, they fight through adversity and win even when the odds are stacked against them.