The month of May largely derailed the Miami Marlins season. After struggling mightily through the second month of the year, the team was never able to get back on track. In many ways, their struggles that month led to the departures of David Phelps and AJ Ramos.
Miami has already started selling at the deadline. In return, they’ve gotten good, but not great prospects. Players that are promising, and could conceivably become Major League contributors, but probably not stars.
You need to look to further than their notable absence on the MLB top 100 list for evidence.