This could be a win-win for the Cardinals and their fans.
By rewarding early purchases and cutting the price of sparsely-attended contests before the event begins, fans can really find opportunities that put them in the ballpark at more affordable prices. The organization can reap rewards in adding to their attendance figures, and adding an even more loyal following as fans find the ballpark more accessible to them. Increased attendance adds to income not only through ticket sales, but also through more indirect means like concessions, advertising, et al.
I don't know how Busch is situated in St. Louis, but I know this would be killer for additional revenue in a city like Denver.