He gassed against Rahman and got stopped on his feet while defending himself. Not quite sleepwalking like Morrison.
Nate Tubbs is not "someone". He is Tony Tubbs' brother! (yes, sarcasm) And he was actually pretty well thought of as a talent. In Corrie's other significant prime loss to Rahman, he had Hasim down in the 3rd but gassed and was stopped while on his feet. Hasim called him the hardest puncher he had ever faced. I wouldn't say his chin was bad. Vitali hit him with some pretty devastating shots and he hung in there. He just got clipped once. Other than that, his problem was stamina and pacing. Morrison had both those AND a bad chin.