The D-backs manager, though, did acknowledge that the strong finish by reliever Chad Qualls gives him a leg up at retaining his closer's position heading into Spring Training next year.
Qualls took over the closer's role from Brandon Lyon on Sept. 13 and since then has appeared in five games and gone 4-for-4 in save opportunities. The right-hander has allowed two hits in five scoreless innings over that span.
"Based on what he's accomplished, especially here as of late, I don't see why he wouldn't be the favorite going in to Spring Training next year," Melvin said.
The complexion of the D-backs' bullpen could change next year with both Lyon and Juan Cruz eligible for free agency. It's likely that Cruz will get a multi-year offer elsewhere and move on, while Lyon could possibly accept salary arbitration should the D-backs offer it to him.
Jon Rauch is under contract for next year while Tony Pena and Qualls are eligible for salary arbitration.
"I don't discount everybody coming back," Melvin said. "We'll see how all that plays out. For me, it's still a talented bunch. Whatever the mix is going into next year, we feel like we'll have quality arms."
Steve Gilbert is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.