We noted during WWE Backlash last night how there was no attendance announcement made at the start of the pay-per-view broadcast. WWE also did not announce attendance for Saturday's WWE NXT "Takeover: Chicago" event, which took place from the same venue as Backlash - the Allstate Arena in Rosemont, IL.
WWE reportedly had around 9,500 Backlash tickets sold before they started announcing matches and ended up with around 9,800 - 10,000 tickets sold. It was believed by some that a sell out for Backlash was a given but that was not the case.
The Allstate Arena can usually hold more than 18,000 fans for a pro wrestling event. A September 2016 RAW live event drew 9,500 fans while a March 2016 RAW episode drew 10,800 fans. The 2014 Payback pay-per-view had an announced attendance of 13,311 fans while the 2015 Extreme Rules pay-per-view had an announced attendance of 14,197 and the 2016 Payback pay-per-view had an announced attendance of 13,250.