The on air people are mostly at the AM stations. CBS owns a bunch of these heritage AM stations that, for the most part, have been fully staffed for a long time. But their ratings are starting to slip as their audience ages, and there doesn't seem to be a future for AM. CBS can spend millions on KNX, but it's not going to change their situation. So why spend the money?
The other area where people got laid off is Radio.com. I know some people at CBS Interactive, and they had extremely high hopes for this site, and that creating original content for the web might be lucrative. Unfortunately we're learning that spending money doesn't always lead to a return on investment, especially on the internet.