Arsenal's failure last season is an important lesson, not long ago Arsenal always played well and consistently but for some reason they failed to get a win from the last two matches they lost in a row which made them lose points and fall from the top of the standings, that is what Arteta must learn that Arsenal need lots of good players to be able to play to replace injured key players. The competition for the top four is very tight which is why this season looks very interesting to me.
Arsenal are repeating their mistakes of last season after they got 3 defeats and 1 draw from the last 5 mtches they played. They were at the top of the table before, but now they have to occupy 4th place after consecutive defeats. Arsenal will have to pick themselves up soon if they don't want to fall further behind in the race for the title this season.
They still have a chance to do that and they should be able to make good use of the opportunities they still have.
I don't know why they still can't anticipate things like this, I mean when entering the middle of the season they always lose stability and make them have to lag behind other clubs that have more stable performances.