The club is expected to announce its roster Tuesday, but it sounded like it would go with 11 pitchers again.
"With a seven-game series, I think it would be more difficult, even though we have the off-days to go 10," Melvin said.
As for the rotation, Melvin did say that Brandon Webb would be his Game 1 starter, but declined to get more specific.
"We'll have an announcement on [the roster] and the rotation tomorrow," he said.
In the NLDS, left-hander Doug Davis followed Webb, and Livan Hernandez started Game 3 with Micah Owings slated for a Game 4 that never came.
Owings, who hasn't pitched since Sept. 27 when he beat the Pirates, will pitch for the D-backs' instructional league team in Tucson, Ariz., on Tuesday to try to stay sharp.
It was in answering a question about Owings' possible rustiness that Melvin seemed to give out more information than he intended.
"Try to get him quite a few pitches to where if he potentially had to pitch Game 4, which I will announce maybe tomorrow, he would be on schedule to pitch that one," Melvin said. "But now I'm getting ahead of myself."
Hello? The bullpen has been a big strength for the D-backs this year, with Tony Pena, Brandon Lyon and Jose Valverde forming a potent combination in the seventh, eighth and ninth innings.
"Performance wise, I think the thing that has really helped them is that Bob has kept them in consistent spots and consistent roles," D-backs pitching coach Bryan Price said.
Knowing their roles and when they are going to be used, Melvin believes is key to a bullpen's success.
"They know when that phone rings who it's going to be for," Melvin said. "When there's indecision when the phone rings, who it's going to be for, sometimes it creates a little uncertainty. With our guys, if we have a lead after the sixth and that phone rings, Tony Pena can pick it up. Brandon Lyon can pick it up in the eighth and Jose Valverde in the ninth. None of them do, but I think they have a pretty good idea when it rings."
Scheduling: This year's NLCS includes an extra day off between Games 4 and 5, but Melvin said he doesn't think it will have a big impact.
"It just makes it a little longer," he said. "I don't think it does anything as far as our pitching matchups go. It just makes for a little more rest and a longer series."
Choo choo: The Rockies won 13 of their last 14 regular-season games, then beat the Padres in a one-game playoff before sweeping the Phillies in their NLDS.
Melvin has likened them to a freight train with the momentum the Rockies have, but what effect the four days between series will have on that is unknown.
"The one that they did lose was to us, and that was with Webby," Melvin said referring to Arizona's 4-2 win Sept. 28 in Denver. "So hopefully the little bit of a layoff now cools them down some."
Said Eric Byrnes, "I think we're two comparable teams. They're playing very well right now, but I don't think we're playing too shabby ourselves."
Close call: The Rockies own the season-series edge, 10-8, over the D-backs. The two teams also played five times during Spring Training.
"We know them," first baseman Conor Jackson said. "They're kind of like our brother squad. Their offense is definitely going to be a tough offense to stop. I think we can match them. At the end of the day I think it's going to come down to who has one more run."