CBS Stations up for Sale

CBS announced that they are going to be selling some of their radio stations that are set in smaller markets. Seven of the 39 to count are country stations in Cincinnati, two in Kansas City, Columbus, two in Buffalo, and in Fresno.
The purpose of selling these stations is to maximize the performance in the radio stations in the larger markets.
This has raised some questions since they apparently are not selling other stations that are outside the top 25. For example a station in Hartford is ranked #50 and it is not up for sale.
There are also small market radio stations that are in cities that are similar size or smaller that are not being sold. For instance San Antonio and Austin have stations that are selling whereas Las Vegas and Charlotte are not.