The Gunners blew a two-goal lead to draw 2-2 at Vicarage Road, but Merson thinks the result could've been better had if not been for Emery.
"People will say there were experienced players on the pitch, but he's the manager and they're paid to listen to him. You can't have a manager give instructions on how to play and then they go out and do their own thing. There would be mutiny, so they're listening to him and he's not getting it right.
"His substitutions weren't right. They needed to keep the ball in that game but they kept giving it away cheaply. The only player who didn't give the ball away all game was Mesut Ozil. You just knew that Arsenal needed to score another goal but he was bringing youngsters on in a game when you're under pressure."