Cruz couldn't adjust and Cody took his movement and offense from him. How? I don't exactly know. Cruz was walking, standing still, not taking him down; essentially not doing any Cruz things. Now I'm a Cruz nuthugger so I'm going to throw this out there: Cruz was looking slow and plodding from the very start, which does not bode well when you've got little finishing ability and traditional boxing skills. Cody managed to convince Cruz that the TD wasn't an option, and since Cruz wasn't moving like a pendulum either he had nothing to go for.
My diagnosis is very fucking solid footwork by Cody coupled with legit cardio and power that puts the fear of god into lesser men. He faced a worn out Cruz who was saved only by his goat chin.