For now, the projected rotation for the first series is Ricky Nolasco, Nathan Eovaldi and LeBlanc.
"As of right now, it would go Eovaldi [second] and LeBlanc, who is set up to pitch that last game," Redmond said. "That could change. We're still trying to piece it together."
The picture will be cleared after Jacob Turner's start Sunday in Grapefruit League play against the Astros in Kissimmee.
Turner is competing for the fifth spot, along with non-roster invitees Kevin Slowey and John Maine.
The Marlins open at Washington on April 1, with Nolasco matched up against Stephen Strasburg.
On April 3, Eovaldi will pitch against Gio Gonzalez.
A primary reason Redmond is planning on throwing LeBlanc third is because LeBlanc would offer a completely different look to the Nationals from the hard-throwing Eovaldi.
LeBlanc is a soft-throwing left-hander who changes speeds and relies on control.
Henderson Alvarez is the tentative choice to face the Mets at Citi Field on April 5.
The Marlins are planning to use all five starters from the start of the season, even though they had some flexibility to shuffle the rotation because of off-days April 2 and April 11.
Joe Frisaro is a reporter for MLB.com. He writes a blog, called The Fish Pond. Follow him on Twitter