4. Erick Rowan
Odds 15/2Argument For From a storyline perspective, Rowan is the common sense choice to be the 3rd man (although given this is the WWE were talking about, that presumably makes him less likely to appear in this match). As a former Wyatt family member, who has feuded with Luke Harper since leaving them, it would make perfect sense that he would become involved this current rivalry.
Argument AgainstIt was reported that when Rowan injured his arm back in June it was likely to keep him out of action for the rest of 2015. Now its not unlike the WWE to bring Superstars back from injury earlier than expected (just take a look at John Cena's career), Night of Champions probably comes a good bit too soon for Rowan to be thinking about making his return.
Prediction Rowans odds give him a decent enough chance of being the 3rd man and indeed if he has recovered from his injury earlier than expected he should be a shoe-in for this spot. Unfortunately, it seems highly unlikely that Rowan will have been cleared for a return this soon after his injury.