The thing is, I don't know if this is completely fair.. But it does streamline the whole process.
As for Pec Zwolle, Cambuur, Go Ahead, Willem II and Excelsior, yes they've been at the top of the Jupiler League for quite a while, but then you need to consider VVV and Volendam in that bunch as well, but suddenly FC Dordrecht promotes, because of one incredibly good season.. while having been obscure for the majority of the past 19 years.
With Zwolle, Cambuur, Go Ahead. VVV and excelsior I can relate. As for willem II, they are more or less an Eredivisie team because they have spend 8 of their last 10 years in it. Volendam they have good seasons and so-so seasons in the Jupiler league.
Neverteless I think Dordrecht deserved the promotion, and with the two in two out system they would have been promoted anyway, and honestly I believe the team on the second place should promote. By far they played the best football through the season. And honestly even if Sparta has the name, the number 16 should have NO chance at all to promote. It was honestly a disgrace they even got this far. Same can be said about NEC who got relegated by them.
It's funny, in spain a team promoted to the la liga who have never played there before. They are called Eibar. they did that with a solid organisation, good football, and no debts. Sounds a bit like dordrecht, although their stadion is a bit bigger with 5.5K seats.
But like I said, three clubs meeting the drop is the result of clogging promotions. We can pretend it is a strange thing, but several teams got kept in the Eredivisie by luck. (roda JC 2009/2013, VVV 2011/2012, willem II 2010 (only won after extra time) With the other one usually relegating aswell. Honestly I am not that surprised and it was just a matter of time before this happened. And I think next year you better avoid spot 16-18 aswell because relegation play-offs will probably mean relegation.