Emery's side lack stability at the back.
Merson sees a big gap between Arsenal and the teams above them.
Arsenal legend Paul Merson says his former side will get thrashed really soon because of their poor defending.
The Gunners made it nine wins on the bounce after beating Fulham 5-1 at Craven Cottage over the weekend, as they moved level on points with north London rivals Tottenham - who are just two points off the top three (Liverpool, Chelsea and Manchester City).
However, Sky Sports pundit Merson believes "Sooner or later" Arsenal "will be on the end of a big score".
"Sooner or later they will be on the end of a big score - defensively they are all over the place," he said.
"The one thing that gets them out of trouble is that they're always going to score goals. But defensively, they are just not good enough."