Any fighter who tries to pull the Old Vitor move of running at your opponent throwing a flurry risks running into a fist. That includes Werdum and Aldo. Their opponents did not cover up and back straight up, cowering from the blitz. Instead they kept their eyes on the target; their opponents jaw, which was wide open. Additionally, nerves and pressure of the big fight appeared to play a role. In Barao's case, I believe lack of heart and confidence played a role as well; unfortunately, Stephens was lacking neither.
But I'm no expert, I just pretend to be one online.