Take Katy out of 2011 and add Gaga and I agree. People might've watched for Rihanna in 2012, but there's not much to brag about considering the 50% viewer drop. Miley brought in viewers but I don't think people expected her to give that performance. Gaga and Katy were the main promos for 2013.
Yet you like to relevantly leave out the fact that when the show was airing, it was the same time Barack Obama was speaking as well but keep your delusions if you think Rih can't pull a crowd.