Apart from Manchester City, other major teams have performed really badly in the last Premier League season. In the next season, those teams will want to build themselves up so that they can correct their mistakes and perform as well as Manchester City.
I don't agree with your assumptions, I think Arsenal and Manchester United had good performances last season, but they can't compete with teams who have a high level of consistency like Manchester City. Arsenal failed to maintain consistency due to the pressure exerted by Manchester City, but that's only normal because Manchester City is the better team.
Without a doubt, no other major team in the Premier League performed as well as Manchester City did last season, but if you're saying that any other team did poorly, I think that's incorrect because there are many teams that perform very well. It's just that Manchester City had already taken the lead by that point, their season had been fantastic, and their team was excellent, unlike the others, which is why they won the title. You can only claim that there is no team that performed as well as Manchester City did in the Premier League last season, and I will agree with you on that one.
However, as @skarais has pointed out, other teams like Arsenal, Liverpool, and others also performed well but were unable to handle the pressure posed by Manchester City, therefore I believe you should continue to consider how some other teams fared the previous season. I think you'll obtain the right evaluation of the performance of other teams.