Let's take a look at the 2011-12 season (the sixth overall) of 30 Rock on NBC.
|Thu 8:00, Thu 8:30||1.2||1.54||2.0||-32%||65||flop||detail|
Rating the Ratings: This season was certainly the beginning of the end for 30 Rock. It got held for midseason, put in the lead-off spot for the first time on Thursday, and was quite unimpressive in that role against a fast-blossoming The Big Bang Theory. When Community came back in March, 30 Rock made its return to 8:30 for the first time since fall 2010, but it was clearly a weaker show than when it had made significant gains on its lead-in back then. This time, it only managed to about equal Community on average. It looked to me like it was time for this show to go, but NBC is giving it one last short season back at 8:00. I'm perhaps being a bit too kind with this grade, but its timeslots this year were easily the toughest it's ever had. Grade: D+.
Here's the now updated War of 18-49 post for 30 Rock.