Source: The Wrestling Observer
As previously reported, Sting was told by WWE that he would be used at SummerSlam to team with Roman Reigns and Dean Ambrose against the Wyatt Family. He got himself in “ridiculously” good shape but was later told he wouldn’t be needed for the show after all. It’s believed that the reason Sting was left off the card is because WWE felt there was enough star power with Cena, Lesnar, Undertaker and Stephen Amell.
WWE may wait until Night of Champions to bring Sting back, since they’ve been trying to increase Network subscriptions by bringing in names like The Undertaker for SummerSlam. Once Erick Rowan is cleared to return, Sting could be brought in for the six-man tag as planned.