It got ugly for CBS last night when, in its second outing, midseason dramedy Chaos (0.9/3 in 18-49, 5.6 million viewers) fell 18% from its underwhelming premiere to finish a distant fourth at 8 PM in adults 18-49, behind a Kitchen Nightmares repeat on Fox. Chaos also pushed down CSI: NY (1.6/5, off 11%, 9.4 million) and Blue Bloods (1.5/4, down 12%, 10.3 million). As a result, despite Shark Tank (1.2/4) slipping 9% from last week, ABC’s unscripted lineup (1.4/4, 4.7 million) edged CBS’ scripted series (1.3/4, 8.5 million) in 18-49 for No. 1. In doing so, ABC hit a 13-week high on the night in 18-49. The season finale of NBC’s Who Do You Think You Are (1.3/4, 5.8 million) held steady and won the 8 PM hour in both 18-49 and total viewers. NBC (1.3/4, 5.6 million) was tied with CBS for second place in 18-49. Fox and the CW aired repeats.