I was also a bit surprised with them, especially AZ. a week ago that team was on top, but maybe because their concentration is split in the confederation Europa league they can't control and hold the position on top, then lost at home vs Feyenoord.
I believe that the problem was not lack of concentration, the opponent was more effective in scoring goals, just see that the opponent scored 3 goals, this overwhelming number of goals shows that Feyenoord was more superior on the field and AZ will need to work hard from now on because the other teams that are below them don't have a big difference in points, if they lose two games it will be enough for other teams to approach them
So, I think if AZ and Feyenoord are capable to compete with Ajax and PSV, the competition would be balanced until the last session.
looking realistically I doubt they will be able to keep up with Ajax and PSV, both Ajax and PSV are very strong teams and they score a lot of goals, it is not easy for other teams to compete with Ajax and PSV unless the other teams are bought by some rich and hire good coaches and good players, only then the other teams would be strong and the league would be more competitive
We will see the race between them, of course, if Ajax is still unstable with coordination.
ajax has already recovered, look at their results from the last 2 games. they won and are at the top, of course they will be champions