Maybe it's because their national feed is now called America's WGN Superstation or something like that and things around the country are a little fuzzy at the moment.
Or maybe it's those Angels in the Outfield keeping the Cubbies on top you're almost seeing?
Its wgn.. they need new encoders bad.. especally on their OTA feed. They are aware of the issue but unfortunatly with the trib going bankrupt, they cant afford to upgrade.