Let's give them one more season before you draw your conclusion. Arteta have bought good and quality players this summer, and I believe that will change the whole mentality of the team. With the current set of players, Arsenal has the highest advantage to win EPL next season, because they have finished three consecutive seasons as runner up. It shows that they have the experience and players to win the title next season.
Liverpool performance in the last season was quite good and the way they performed were admirable. Liverpool's performance made the fans and gave other opponents a strong competent. And the perception was made based on that performance is still going. But this season the team Arsenal is going too well and the expectations and the hopes of the fans and viewers are now changing. I think this is necessary to make a step forward to accept the changes and challenges because nothing is constant in this world. Arsenal seems very active in the transfer window and they always try to get the best players to make their club even stronger. I think this is not only in words but they are really doing very well. But still perfection is not so easy and possible. There are some weak points where they still need to work hard for a secure bright future.