Let's take a look at the 2012 season (the eleventh overall) of American Idol on Fox.
Rating the Ratings: For the last several years, American Idol made some tweak to its formula that got everyone wondering whether it would kill the ratings. Though the show did decline, realistically none of those declines were remotely alarming; they were all pretty close to the rate at which primetime series programming declined on average. So it's kinda funny that the year Idol made no discernible tweaks was the year Idol finally took a huge dip. But while nothing really changed internally, it was the change in the primetime environment - namely a flood of new music competitions entering the landscape - that seemingly finally put a dent in the beast. Apologists will note that Idol remained the #1 entertainment program and that that's still really impressive for an 11th season. Sure, but it was a lot more impressive when it was in its 10th season and still well over 50% ahead of every other entertainment series. In season 11, Idol's Wednesday edition beat Modern Family by just 6%, and the Thursday edition actually finished behind other entertainment programs, something that hasn't happened for an Idol night in nine years! This season was "still impressive," but I think that's more telling about just how far ahead Idol was coming into this season, not about this season in particular. And I'm grading seasons here. Grade: D.
Here's the now updated War of 18-49 post for American Idol.