Charlie's Angels may not be long for this world. The ABC series was Thursday night's lowest-rated show as ratings plunged 20 percent.Grey's Anatomy hit an all-time low 3.0 rating and 8.5 million viewers, and Private Practice sank 25 percent to a 2.1 and 6.2 million viewers.Most shows took a dip, thanks to the baseball playoffs on TBS. Falling slightly, The Big Bang Theory pulled in 13.6 million viewers and a 4.4 to win the night in both categories, but, once again, How to Be a Gentleman failed to hold on to its lead-in. The comedy drew 7.82 million and a 2.5 rating. Person of Interest also notched a 2.5, but snagged 11.46 million viewers. At 10/9c, The Mentalist was the only show to enjoy an uptick, rising 4 percent to 12.9 million and a 2.7.The X Factor (11.2 million, 3.8) continued to perform steadily enough for Fox to win the night. The show was down just 3 percent.The Office (5.71 million, 3.1) posted its worst numbers in six and a half years, but was the Peacock's best performer. Community (3.4 million, 1.5), Parks and Recreation (4.13 million, 1.9) and Whitney (4.88 million, 2.3) all dropped, while Prime Suspect (5 million, 1.5) shed eyeballs, but was even in the demo. On The CW, The Vampire Diaries (2.55 million, 1.2) and The Secret Circle (1.96 million, 0.8) fell 8 and 20 percent, respectively.