Mattingly inherits a talented core, but he joins a team that seeks stability after so many managerial changes. The 54-year-old is the 11th manager the Marlins have had since Jeffrey Loria became owner in 2002.
In 2015, the Marlins opened the year with Mike Redmond in the dugout and replaced him with then-general manager Dan Jennings on May 18.
"With all the uncertainty we had this year, with Red and with D.J., we wanted some stability," said president of baseball operations Michael Hill. "We wanted someone our players could identify with as a leader, someone they could rally around, someone they felt they could grow with and have success with."
Now that the Marlins' top priority has been addressed, here's a look at five other pressing topics the organization faces.
Coaches: Tim Wallach, Mattingly's bench coach in Los Angeles, is expected to have the same title in Miami. First, the Marlins are seeing how the Dodgers' manager search plays out. Wallach is a candidate. But if he doesn't get the job, look for him to move to Miami.
• Wallach expected to be Mattingly's bench coach
As for hitting coach, Frank Menechino is expected to return for his third season. Menechino is finalizing his contract to stay. Also returning from the 2015 staff are Perry Hill (infield/first base), Reid Cornelius (bullpen) and Lenny Harris (assistant hitting). The team also must fill its pitching coach and outfield coach vacancies.
Analytics department: With so much data available, the Marlins want to tap into as much information as possible as they make their evaluations. The process of putting together a department continues.
Revenue streams: Payroll projections are roughly $80 million for 2016, but the organization is pushing to increase those numbers in future years. Team president David Samson is on record saying the team is actively working on a naming rights deal for Marlins Park, as well as a new local television deal with Fox Sports Florida.
Developing pitching: It's no secret the Marlins are in the market for pitching, ideally a top-of-the-rotation candidate and a potential closer. Internally, they are emphasizing improving the development of arms already in the system. This is where the hiring of Jim Benedict, previously with the Pirates, as the vice president of pitching development comes in.
Benedict has the reputation of being able to fix pitchers' mechanics. He will have input with the big league squad and in the Minors. One of his tasks, for instance, will be helping prospect Jose Urena, who has a plus fastball, to further develop his breaking ball.
Bringing in fences: The evaluations of Marlins Park, one of the most spacious ballparks, are ongoing. The team is exploring moving in and lowering the fences. Any changes are projected to be done before Opening Day.