Biggest problem with Tampa baseball is a fair share of people are snowbirds and leave in the summer (Lightning are number 1 team in city even ahead of the Bucs) and like someone said a lot of people are from somewhere else and already have teams. I've gone to Tampa/Clearwater a few times and almost all of the locals I meet are from up north who moved there.
Also the summer time is so hot you need to have a roof of some sort like Houston or Miami. Not many people are going to want to sit there when its 35 Degrees and 80% humidity.