Many times an important game on cable (ESPN, TBS, etc) is carried locally by an independant over-the-air station who has contracted to show the game to local viewers. NFL Network does this. WGN, by the way, has both a cable feed and an over-the-air feed so it is possible that they will sometimes send one type of programming up to the nationwide satellite/cable audience but a different feed of local interest over-the-air to Chicago customers. What you say may be true but it is also possible that the C*bs game is being broadcast to the local Chicago area over the air.

"We don't do anything easy. We're the Astros." - Craig Biggio