According to Joe Frisaro of MLB.com, the Miami Marlins are considering making hitter friendly changes to their fences next season in an effort to boost extra base hits. This includes both moving the fences in and shortening the height of the walls. In particular, center field seems unreasonably large, both by distance and the size of the wall:
According to hit tracker, Marlins Park has the lowest HR per game total in baseball this year at 1.29 (NL average is 1.88). This includes home runs hit by both the Marlins and their opponents.
It has also been a difficult park to hit doubles in. Joe Frisaro wrote,
As an organization, the Marlins have believed, with its wide gaps, the park would lend itself to more doubles. But that hasn't been the case. The Marlins rank last in the Majors in doubles at home, with 87. Since 2012, they've hit 460 doubles in Miami, which ranks 26th.
One theory some players say is because the park plays so big, outfielders play deeper than in most places, essentially playing a "no-doubles" style while being at normal depth.
Because defenders are deeper, they will concede a bloop hit over a liner into the gaps.