This is odd. It probably means the login has failed for some reason. I am currently listening to WGN and the Cubs. If you are willing to try something, download the attached mlbviewer_gui-0.2010.1_debug.deb and install it. It contains some extra output. You'll need to start it from an xterm windows with the following:

python /usr/lib/mlbviewer_gui/mlbviewer_gui.py

Copy the output here (it will contain HTML).