Despite a revamped judging panel featuring new judges Kelly Rowland and Paulina Rubio, ratings plummeted on Wednesday and Thursday for the season premiere of Fox's The X Factor, dropping more than a third from last year's opener among the key 18-49 age group and nearly 20 percent among total adults. On Thursday night the talent contest was clobbered in the ratings by a rerun of CBS's The Big Bang Theory, which drew 8.53 million viewers to X Factor's 5.94 million in the 8:00 p.m. half-hour. On both nights it also came in behind CBS's Big Brother. The ratings collapse appeared even more striking in face of the fact that it did not have to compete against NBC's powerhouse The Voice this year as it did last year.