Baron Corbin vs. Kalisto was originally scheduled for SummerSlam but the plans for that match were scrapped because they had other matches that they wanted on the show. That is what was reported in the latest Wrestling Observer newsletter.
As seen in the promo below, Kalisto was not in Brooklyn and WWE is claiming that he is injured. WWE talent has been announcing their own injuries on social media in an effort to blur the lines between work and shoot so I don’t know if the Kalisto injury is legit or if he couldn’t make it out to Brooklyn for some other reason. The Samoa Joe injury at NXT Takeover (with the referee doing the “X” gesture) was also a work.
— WWE (@WWE) August 21, 2016