As anyone with a shred of radio experience knows, news and talk formats don't spike overnight like new music formats. CBS is in for the long haul, which is a minimum of three years. The history of successful news/talk stations is littered with three to five year ramp-ups. KIRO in Seattle went news/talk somewhere around 1974, and didn't hit number 1 until around '78. It then stayed there for most of two decades.
I worked at WTOP 20 years ago at the absolute nadir of its execution of all-news (anyone remember the pan flute sounders?). It got better, with a vengence, over the past decade or so.
Any angst or glee over WNEW's lack of ratings a year into the format is a waste of time. Much like the 5 minute I've wasted writing this post.