It's a book out there about how networks like Fox, WB & UPN start with an overwhelming amount of Black programming when they start to gain viewers and then abandon that demographic as soon as the station pops.
Here's an article "
This Isn't The First Time Network TV Discovered Black People
NPR Choice page
Here's the book
Color by Fox
"The result was that even the shows trying the hardest to deal with thorny racial themes on screen?such as Roc, South Central and New York Undercover?were, sooner or later, forced by the network to avoid controversial or unconventional material. Often the shows were canceled outright, or control was given to white producers."