Reliever Bryan Morris, who has not pitched since May 24, was reactivated from the 60-day disabled list Tuesday and then designated for assignment.
Morris, 29, pitched in 24 games this season before undergoing surgery in June to repair a herniated lumbar disc. In his third season with the Marlins, Morris compiled a 3.06 ERA in 17 2/3 innings pitched.
The Marlins would have liked to keep Morris for the remaining two weeks of the regular season, but it would have meant dropping another player from the active 40-man roster.
"The main thing was we didn’t have any roster spots," Marlins manager Don Mattingly said. "We were in a tough spot. For him to be activated meant someone else would have to go home."
Morris, whom the Marlins acquired in a trade with the Pirates in 2014, avoided arbitration this past offseason signing a one-year, $1.35 million deal.
His agent, Jim Kuzmich, said Marlins President of Baseball Operations Michael Hill “asked us to keep them in mind” when he chooses a new team in the coming months, if he’s not claimed off waivers in the next two days.
If nobody claims him, he could accept the Marlins’ minor-league assignment and become a free agent this winter.
"Bryan’s a guy we like and he’s capable and still has a chance to be part of our future," Mattingly said.
Morris said in recent weeks he had felt better physically than he had in the past two years following the surgery.
Morris was 9-5 with a 2.30 ERA in parts of three seasons for the Marlins. He has pitched in several simulated games recently as part of his rehab.
Morris isn’t the only reliever that may not be back in a Marlins uniform next season.
The two-year, $5.8 million contract extension Mike Dunn signed in 2015 is up after the season.
Dunn, 31, started his sixth season with the Marlins on the disabled list missing the first two months with a forearm strain.
Dunn, who has made a franchise-record 400 career appearances with the Marlins entering Tuesday’s game, has gone 4-1 with a 2.84 ERA in 38 innings since his return from the disabled list.
Fernando Rodney, who will turn 40 on March 18, has a $2 million option for next season that the Marlins could choose to pick up.
Rodney, however, has not pitched well since the Marlins acquired him in a trade with the Padres on June 30.
In 35 appearances (32 2/3 innings) with the Marlins, Rodney has compiled a 5.79 ERA with eight saves in 11 opportunities.
Over the first three months of the season, Rodney converted all 17 of his save chances with the Padres, allowing only one earned run (0.31 ERA), which earned him All-Star recognition.
A.J. Ramos, who turned 30 on Tuesday, and David Phelps, who turns 30 on Oct. 9, are both arbitration eligible next season, and likely to remain key parts of the team’s late-inning relief.
Phelps (7-6, 2.42 ERA) has proven his value as both a starter and in a late-inning setup role this season.
Ramos (1-3, 3.00 ERA in 60 innings), who earned his first All-Star nod this season, had converted 38 saves in 41 opportunities entering Tuesday.
Other key relievers such as Kyle Barraclough and Nick Wittgren are still under team control.
Wednesday: Marlins RHP Tom Koehler (9-11, 3.96 ERA) vs. Nationals RHP Max Scherzer (17-7, 2.78 ERA), 7:10 p.m., Marlins Park.
Thursday: Marlins RHP Jose Urena (4-7, 5.59 ERA) vs. Atlanta Braves TBA, 7:10 p.m., Marlins Park.
Miami Herald Sportswriter Barry Jackson contributed to this report.