Frankly, I'm not sure when WBBM hit rock bottom, but the Johnson/State duo immediately preceded their most successful period in a quarter century. Anne slowly got demoted off newscasts until Rob was going solo all evening. Meanwhile, CBS primetime was blowing up, and WMAQ was dealing with the tandem troubles of a rocky 10pm anchor change & The Jay Leno Show. WBBM became an unchallenged #2 for most of the 2009-10 season. In addition to a new midday anchor team (Porterfield/Tellez), they used this momentum to hire Kate Sullivan, reinstate a normal morning news, and reunite Bill and Walter. All good ideas, but then NBC5 recovered, and most decisions since to stop the bleeding just further flung them into the abyss.
At 10, WBBM typically trails WGN by a few tenths of a point, both settling in the 2.5-3.0 range. WMAQ beats that by a point or two, and WLS sits between a 6 and 7.
At 9pm, WGN typically beats FOX32 with like 4.0 to the low 2's.