Vocativ has a good article running down the basics of spring training economic impact, which could probably best summed up as “there isn’t hardly any.” Key paragraphs:
“There’s just no evidence that it does anything,” Philip Porter, an economics professor at the University of South Florida, said, noting that such studies overlook the costs—opportunity and real—of such investments.
After the 1994 baseball strike curtailed the ’95 spring training season and diluted its quality for most of the duration with replacement players, University of Akron professor John Zipp assumed he’d see a negative economic impact because spring training attendance declined 60 percent—he didn’t.
“It’s a wonderful experience,” Zipp said. “It’s just not worth public dollars.”
Lots of other good stuff there, including the tale of two neighboring cities battling for the right to put $50 million in public money in the pocket of the Boston Red Sox. (I wish it went a bit into possible explanations why the economic impact of people attending spring training games is near zero — leading theory is that it doesn’t much increase the number of spring tourists to Florida, just changes where they spend their money — but you can’t have everything.) Go read it, then bookmark it for the next time a baseball team insists that it needs a new spring training facility and that it will more than pay for itself in new tax receipts, because that shit is messed up.