There are several factors at play. First, there's a lot of familiarity with Mesa: there are a lot of Cubs fans retired there, and many players have a second home in the area. Second, Mesa officials have been extremely solicitous of the Cubs' needs and has been a good tenant for the team in years past.
Why the delay? We're told the Board of Directors is waiting to hear more about state approval of a Maricopa County sales-tax hike before burning any bridges with Naples and Collier County. If the hike in the sales tax is approved, about $80 million could be earmarked for the ballpark and spring-training complex; another $40 million for surrounding development would come from the private sector.
Plus, there's the logistical issue of building a new spring-training ballpark in Florida, even with funding approved. State law requires that the state approve any new facility seating 10,000 or more. Avoiding state review is one big reason why Lee County and the Boston Red Sox decided to go with a new ballpark seating only 9,999; once the state gets involved things slow down. There's no way to avoid this provision, either.