Our league results are occassionally bad by underperforming because of complacency. Players repeatedly stated they're having trouble motivating themselves to play bottom teams, because of the lack of quality opposition.

You're also dismissing that PSV aren't a bad side. They were in a group with two semi-finalists and Inter. And Ajax can win every game in the Eredivisie by 4-0, but if PSV wins them by 1-0, Ajax are clearly the better side, but the league table would be the same besides goal difference.

The last point is also the main problem I see with Ajax challenging in a better league. Ajax played almost everything this season with the same core of 12-13 players. They're severely lacking squad depth.