It’s clear that casual fans drive attendance figures. Diehard fans are going to games regardless. The casual fans are the ones that need convincing.
I argue that it is not the Casual fan who drives baseball attendance in Cleveland, but the diehard who is willing to fork over a large capital investment for season tickets.
The MLB Avg for season ticket holders per team is around 15,000, and the Indians currently have lower then 6,000, during the hey day in the 90s they had around 22,000. So every single night the Tribe has a 9,000 seat disadvantage from the average MLB teams attendance, that would be tough for any team to make up in Causal/walkup fans on a nightly basis.
If the Tribe ever wants to be anything less then the bottom of the barrel in attendance they are going to need to be able to show the diehard's, not the casual fan that they can string together a few successful seasons, and warrant forking over a large sum of money for season tickets. The team has some work ahead of it , when you have an ownership group who has a history of crying poor, trading back to back Cy-Young winners, and tells its fans it can only compete every 5 years, its tough to get even the diehards to want to commit.
(my number for avg. MLB season ticket holders comes from a WSJ article from '09, couldn't find anything more current but I wouldn't be surprised if its higher today)