Rescue Me was simple yet wonderful in its early seasons. The show was nothing more and nothing less than a bunch of firemen bullshitting and ballbusting in the firehouse as they repressed their problems. We loved watching that. But as Rescue Me wore on and the fundamental building blocks of the show (most notably Denis Leary's character's unresolved emotions regarding 9/11) grew more and more distant, it pressed further into melodrama.
Extreme acts of violence, sexuality, and even arson, became somewhat regular and the show devolved from dramedy into full blown soap opera. While this decline was gradual, season 4 was the tippping point for many viewers and critics, and the show never recovered.