Dave Meltzer of the Wrestling Observer is reporting the reasoning behind why Aleister Black took on Sami Zayn on SmackDown instead of WWE SummerSlam like originally slated.
According to Meltzer on Wrestling Observer Radio, Vince McMahon came in Tuesday, hated the show and totally re-wrote the episode, including the main event. In doing so, they still had an hour to fill so Vince decided to plug Black and Zayn into the match.