So what does the club need moving forward?
Years ago, former catching great Ted Simmons expressed that message to Jennings.
"Ted Simmons said something to me a long time ago -- it takes zero to three years for a player in the Major Leagues before you truly know what type of player you have," Jennings said. "The longer I'm in the game, the truer that statement is. A lot of these guys are in that zero to three threshold, time-wise."
For all their struggles, the Marlins this month are playing some of their best baseball of the season. They're showing signs of life despite Giancarlo Stanton (broken left hand) being on the disabled list since late June, and Jose Fernandez, who started on Saturday, missing substantial time.
"You're starting to see them evolve as players," Jennings said. "What type of players they're going to be. As a manager, you see what type roles you can put them in -- where they fit best in the batting order."
Reliever Mike Dunn said after Friday's 2-1 win over the Nationals that sometimes it takes time for teams to put things together.
"Coming out of a new year with a lot of new pieces, it doesn't always click right away," Dunn said. "This year, I feel like everyone has kind of come together here as of late. That's a good thing. Now we're just playing baseball loose. We're just trying to have fun."
The Marlins are not just using September to see if they can finish as high as third place in the National League East. They are seeing if a majority of this group will be together next season.
"This has somewhat been a learning year, a traditional year that way, due to the changes, the injuries and the different things we've had to go through," Jennings said. "But I think in the end it's going to make us all better.
"I think this team is very close. I think there are a couple of places you can add, in the rotation. But, yeah, I think this team is close. I think they also sense it. That's huge. They have to believe they're good. I think they're starting to feel that and sense that now."