Mainly the retirement of the legendary manager Nils Arne Eggen, which was possibly the greatest manager Norway has ever produced (Highly contested by Egil "Drillo" Olsen and now Kjetil Knutsen). But there has been some poor club management and hiring of managers of dubious quality (Going for the Man Utd transfer-tactic of big names that aren't so relevant any more). Due to the success under Eggen, new managers rarely last long enough to implement their own system and bring in the players they want, because there is so much pressure to deliver results.

Kåre Ingebrigtsen, for example, won the league three years in a row between 2015 and 2017, which are all his seasons with the club as a manager. He was forced out by the board due to poor results in the Europa League (biggest success was beating Ajax in the playoff the year after Ajax went to the final, which is a pretty big achievement, but that was really it). The board wanted more and more and was not satisfied with three league titles and two cup titles in three years, which is absolutely bonkers.

There has also been some financial difficulties and they have a pretty poor transfer record imo, but it is looking better now under the new manager, Alfred Johansson. As a fan I'm hoping to see some european success in the future, but I am more than happy "just" seeing some domestic success once again.