I think Khan broke down Kevin Cunninghams spirit more so then Devon's. I mean, he said some harsh stuff towards the end of the fight to Devon. When a fighter is down, one should boost a fighters morale not degrade it even more. Devon seemed really upset in the post fight interview. He seemed like he wanted to cry. Nothing wrong with that. Defeat is hard to accept after putting in so much work.
He overachieved in this sport with his current skill set. He should be rejoicing for the titles and money that he has made up to this point.
He was trying to get Devon to go after Khan, and told him the obvious, that he was just following Khan around instead of cutting off the ring. Khan literally was just moving in a circle center ring to blunt Devon's "pressure" fighting. It consistently astounds me how many top or near top level fighters come into a fight with a poor gameplan and minimal ability to make adjustments. The book is out on Khan. Devon was not going to beat him fighting like he normally does, period, and he spent half the fight trying that method, then the other half doing a laughable imitation of pressure fighting.
Devon is an amateur-style, high workrate, shoe shining kind of fighter who capitalized on being the quicker man for much of his career. Amir simply had him outgunned at his own game. I'm not surprised he couldn't change the stripes that took hundreds of fights to form in a single training camp; most guys can't.