#1 Inadequate time for the Laca-Auba partnership

Since Aubameyang swapped Borussia Dortmund for Arsenal in January 2018, his link-up with Alexandre Lacazette upfront lead to a number of goals and goal-scoring opportunities for the Gunners.
Emery, too, seemed to rely upon their partnership in Arsenal's pre-season fixtures, as the duo was started together in all games barring one. The pair had eight goals between them in four games.
However, the Gunners' boss decided to bench Lacazette against Man City in a decision that came as a surprise to many. Aubameyang seemed starved off service without the Frenchman on his side and cut a lonely figure in Arsenal's final third.
Lacazette's introduction to the mix infused life in the hosts' attack, and it seemed as if they might take a point off the encounter after all.
However, Silva's strike killed the game for good, and Arsenal's attacking duo did not get enough time to assert their authority on the proceedings thereafter.