Eredivisie 

It is the top Dutch Football/Soccer league. The football league was first made in 1956 and it has 18 teams like any other football league. The top 3 best football clubs there are Feyenoord, Ajax and PSV. It is the 7th strongest football league in the world and Ajax has won it the most with winning it 28 times.

Bob: Hey, you wanna watch Feyennord and Ajax clash in the Eredivisie?
John: Hell yeah!

Eredivisie by F1nnley May 27, 2023

the Eredivisie effect

The Eredivisie effect is caused by a football/soccer player leaving an easy league after playing extremely well to join a better league, and in the process somehow losing his ability. This can sometimes be reversed by going back to an easier league, but if the person affected is young, it is much harder.

Person 1: What happened to Jozy Altidore? He used to be so amazing.
Person 2: It's the Eredivisie effect, he joined a harder league

the Eredivisie effect by OfficialMAN December 10, 2016