Analysts now love the Marlins farm system. Last year, fangraphs.com ranked it 26th in the majors. This year, SB Nation says they're eighth, Bleacher Report 5, Scouting Book 6.
Bleacher Report put it this way: "Over the last year, the Marlins’ farm system endured a 180-degree swing. However, it came at the cost of essentially all their premier big-league talent. Through trades with the Blue Jays, Dodgers and Tigers, respectively, the organization bolstered their prospect pool at nearly every position."
That's kind of like starting a diet by shooting yourself in the stomach.
The other thing is that the prospects, who would mostly be in AA at this point in a class organization like the Cards, are already playing in a big league park.
Here's the rankings from ScoutingBook.com of players listed as prospects but already in Miami, big leaguers, no longer really "prospects": Jose Fernandez (ranked 1 prospect), Rob Brantly (5), Marcell Ozuna (6), Adeiny Hechavarria (8), Derek Dietrich (14). Brantly and Hechavarria were starters from the get-go this year.
So, maybe the attitude to take is to enjoy watching a AA team in Miami this year.