What I noticed at the end of the games was that Atlanta was so observant about a set piece for Arsenal. They rather prefer the ball to go to the throwing side than being a corner. It was just 2/2 corners for both teams before the game ended and the reason for Atlanta being watched over those corners is that Arsenal has created more goal chances during corners. And if they have multiple corners they may end up scoring one and then winning the game. To be honest Atlanta's coach is a good coach and his boys played against Arsenal so well that they deserve more than the draw they got in the game. The penalty would have sealed everything if they had scored it.
Atlanta were just playing base on instructions we all know how dangerous Arsenal as a Club are when it comes to set pieces that will lead to an air attack. Arsenal have players who are very good in the air and this has been one of their routes to getting goals. Last season Arsenal defender Gabriel had 6 goals with which all of them were headed goals from set pieces. Yesterday Atlanta knew Arsenal wanted to use it against them and stopped them from doing, if I can remember the only corner against Tottenham in the league was the goal they got to score and win the match so maybe most teams are actually studying how they arsenal had deployed method to get goals off opponents.
Overall yesterday Arsenal were simply just poor, I think Arteta needs to find solutions to the lack of creativity coming from the midfield in the absence of Their club captain. Against Manchester city it will be very risky to try out a new formation yeh so they could stick to the Tottenham formation for now