"It'd be good for the game," he said. "It would be good for excitement."
The dimensions are currently 344 feet down the left-field line, 386 feet to left-center, 418 feet to center, 392 feet to right-center and 335 feet down the right-field line. Meanwhile, the walls sit high, ranging from 11 1/2 to 13 feet.
Since Marlins Park opened in 2012, Miami ranks 29th in home runs at home with just 192. This season, Miami is tied for 26th in home runs at home with 42, although one player -- Giancarlo Stanton -- has accounted for 13.
"Certain parts of the ballpark, I'm certainly in favor of [moving in]," said Jennings, who served as the Marlins' general manager since 2013, before taking over as manager earlier this season. "I know [president of baseball operations] Mike Hill and I, when we were upstairs, we used to argue all the time.
"When a ball we hit would hit the wall, I'd say, 'Bring them in.'" When a ball was hit by the opposing guy, Mike would say, 'Keep them back.' So we kind of had a running debate all the time. But I think it will help. I think it will help the ballpark play more fair."
Miami's pitchers have fared well in the large dimensions, compiling a 3.66 ERA at home since 2012 (16th best in the Majors), while posting a 4.32 ERA on the road in the same timeframe. Still, Jennings thinks the advantages of lessening Marlins Park's dimensions outweigh the cons.
"If you see Giancarlo or some of our outfielders get a chance to crawl up on the wall and take away a home run, that's exciting," Jennings said. "So if that's what [team owner] Jeffery [Loria] and [Samson] have in plan, then I think that could be fun."
Steve Wilaj is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.