Arsenal level of competition is very high, and they are really trying their possibilities to see that they get a trophy, but unfortunately they are always failing to do that at the end of the season. Although to me, getting more players is not compulsory like for other teams because Arsenal's squad is full of strength and everything is complete, I think they just need to change their pattern of play and some other things because even weak points I did not see from them, but their main problem is winning a title, which they need to win seriously.
So since all they need now is to win a title, they need to come back with a new pattern of play so that they can be able to concur with Manchester City's dominance. It is only Manchester City's performance that always holds them back from winning the title.
If Arteta has tried the same players for two good season and they make a similar mistake, he should never give them a chance to repeat those mistakes again and the players that cost them such losses should be dispose off, if there is offer in the table and it's going to be beneficial to the club, they better sell them, there is going to be more good offers and young once for replacement for the sold players so they can come back next season to give all their best this time for the time.
I am also thinking that Manchester City are winning not just because of Guardiola pattern, it's because of the current squad he has right now. Remember Arteta work with him for years before he start solo playing for Arsenal, he would know better how to handle pattern with Guardiola but the squad is what I think are going to giving him advantage over other teams. Didn't you see even Liverpool almost bag the trophy but they also made the same mistakes Arsenal made and theres was during the end of the season.