Lance wrote a good analysis of both WCBS/NYC and and WBOS/Boston for his "Hotline" column.
The one important aspect it misses is how the music business has changed. Both radio and music were affected by the internet in the 90s. The music industry lost billions in revenue in the early 2000s because fans found ways to get music for free rather than buy it. That led to the entire industry changing from a physical product business, with distribution and retail, to an online business based on royalties. Radio was part of that music eco-system, and is now finding itself on the outside, with less support from record labels and artists, who are more focused on direct relationships with their fans.
This change in the music business has had a direct effect on how music customers see radio. You see lots of comments from fans complaining about the number of commercials, or the amount of music repetition. The fact is that commercial loads and playlist size haven't changed in over 30 years. But peoples' perceptions have. They can now compare broadcast radio with Pandora (which I did over the weekend) and they can hear the difference.
Advertisers can see the bigger picture, of music audiences shifting from broadcast radio to various online services. That shift means less money for radio advertising. Less money means less staff. But that's if you look at music. On the other hand, sports talk is growing, as evidenced by this thread. There's more money in sports talk, thus radio owners are trying to incorporate local sports into their stations. One example is WAXQ adding Jets football. Obviously adding Mets baseball to WCBS was also part of that trend.
Longterm, broadcast radio will have fewer music stations and more talk stations because music has changed and moved online. The entire infrastructure around music promotion that used to involve broadcast radio is in the process of leaving and moving to where music listeners are going, which is online.