Things are starting to get interesting...
From the article:
Cubs President Crane Kenney sent a letter last week to rooftop operators last week reminding them that game day sales violate a City of Chicago ordinance governing the rooftop businesses. The letter was obtained by the Chicago Tribune.
Kenney also said in the letter that it has come to the team's attention that rooftop seats are being sold by ticket brokers and other third parties, another code violation. Only businesses with special club licenses granted by the City of Chicago are allowed to sell admission to their rooftops.
That third party reference - I'm wondering if that's Groupon?