Arsenal has indeed continuously improved their squad depth. While they have consistently failed in several seasons, consistently finishing in second place, the team has never given up and continues to strengthen their squad, which was already strong last season. However, the team has been unlucky, and their players' mentality has sometimes weakened during matches.
Performance improvements will be meaningless if Arsenal lacks the right strategy to win titles, and those improvements will be futile.
Arsenal is overly praised, and rightly so, as they consistently bring in high quality players, but consistently fail to win titles.
Meanwhile, Chelsea and Leicester, who are often underestimated, have both won titles in the past decade.
In my opinion, as long as Mikel Arteta remains at Arsenal with the same strategy, I will always doubt Arsenal, and there will be no improvement for me.
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.