Last week had a huge main event. Sometimes people take a week off, especially with a PPV nearby. This was an episode to set up angles more than anything, so I can see people tuning out after they saw the Bryan-Mox angle (which gained a massive amount of viewers btw, and while Bryan is Bryan, due respect must be given to Mox, who I feel is underrated around these parts). I wouldn't worry about it at all unless it becomes a multiple-week trend, there have been plenty of such one-offs/two-offs .