Not about the club, about board related issues, because it happens that their war is against Florentino, not Real Madrid.
For a Madridista it might look like the same as hating on Real Madrid, but from an outside point of view, it isn't. It all started when *allegedly* Florentino helped Marca take down Calderon, and Calderon had allengiances/asked for help in AS, then the change of term came and most AS journos got nothing from Florentino while Marca were scooping everything ahead of time.
Only went worse as the biggest players AS built a relationship with (Salgado, Raul, Guti, Casillas and such) were being cleaned from the club and they started losing inside information to compete against Marca, leaving them isolated and still attacking Florentino in some edges, which translates to "antimadridista" for a lot of people.