Consistency was a problem for Arsenal last season but I think what Arteta has done in the transfer market this summer is to improve on their weaknesses last season by recruiting several potential players who have the same quality as the core players so that there are no game changes when there is a rotation in the middle or at the end of the competition.
The power of money cannot change, but everything needs a process. After being handled by Arteta, there have been many positive changes for the Arsenal team, and I believe in the process that Arteta is doing to make Arsenal even better.
The Arsenal squad already has good quality, but as far as I know they don't fully have a winning mentality. Arsenal are still struggling to get out of the pressure like last season, but gradually this can be changed as the players mature.
The same thing happened to Manchester City in the Champions League, even Pep Guardiola admits it. In the end experience has given them the mentality that ultimately helped Manchester City win its first title. Arsenal also have the opportunity to do so, but of course they have to learn from past experiences.