#4 Unai Emery's substitutions were baffling
In a game where Arsenal were a goal down, Unai Emery decided to bring on Lucas Torreira to replace Shkodran Mustafi, leaving both Nicolas Pepe and Alexandre Lacazette on the bench. This was Arsenal's last substitution, as an unfortunate injury to David Luiz saw Guendouzi come on before half time and Mesut Ozil was brought in to replace Martinelli in the 60th minute, which was again, unnecessary.
The Spaniard was wasteful with two of his three substitutions last night. Replacing Martinelli, a goal-scoring winger, with Mesut Ozil, a midfielder, and forcing him to play on the right when you have a natural right-winger in Nicolas Pepe, waiting for a chance to shine, is probably Emery's worst decision in a long time.
Arsenal are winless in their last seven games, and this is their worst record since 1992. By the looks of it, Emery's tactics, formations and decision-making isn't helping Arsenal's cause in any way and has in fact only worsened it, as things stand.