1) Midfield has to be strengthened
When you have people writing after the game that the Gunners are missing Granit Xhaka, you know there is a problem in the centre of midfield. Guendouzi and Ceballos may have not done a lot wrong, but they were way too passive.
They allowed Brighton too much time on the ball, but when the Arsenal pair had possession, they did very little with it. They are certainly light of numbers in the middle, at the moment, with Lucas Torreira also sidelined, but the midfield is an area that must be reinforced in the summer.