"Unfortunately, he was the better Wade tonight," said LeBlanc, who gave up three runs (two earned) in seven innings.
Donovan Solano went 2-for-3 in the first game, and he had an infield single in the seventh inning in Game 2, extending his hitting streak to seven games. But Miami couldn't break through against Miley, and despite allowing six runs total in the doubleheader, the Marlins were swept because they managed just two. In Game 1, Jacob Turner gave up three runs in six innings in Arizona's 3-2 win.
The D-backs completed the sweep in the first ever doubleheader at Chase Field. The reason two games were scheduled on the same day at the retractable-roof stadium was due to a scheduling conflict.
Arizona salvaged a four-game split with the Marlins, who outslugged the D-backs in the first two games.
"[Miley] and LeBlanc really were throwing the same type of game," Arizona manager Kirk Gibson said. "We were fortunate to get some runs."
The Marlins are 4-4 on the road trip, which resumes on Friday with three games against the Dodgers in Los Angeles.
Miami leaves Arizona with some unanswered questions regarding its rotation.
LeBlanc, who made 11 relief appearances before joining the rotation, could find himself still starting or going back to the bullpen.
"The kid has pitched well," manager Ozzie Guillen said. "I think we want to take a look at it.
"There are so many things in the air right now. There's things like, use him out of the bullpen, don't use him out of the bullpen, go to a six-man rotation, don't go to a six-man rotation."
Turner, a highly touted prospect, is not expected to pitch in relief. The Marlins may decide to go with a six-man rotation now that they are carrying 13 pitchers.
"I'm going to sit down with the front office and the pitching coach and figure out the next couple of days what is the best thing for the ballclub, and the best thing for the rest of the pitchers," Guillen said.
LeBlanc matched his season high by going seven innings. He also worked seven frames against the Dodgers on Aug. 12, giving up one run, but took the loss.
First-inning struggles hurt the Marlins in three straight games.
LeBlanc gave up a pair of opposite-field singles in the opening frame. A.J. Pollock led off with a hit past Solano at second base. He scored when Paul Goldschmidt sprayed the ball into right field.
"He keeps you off balance," Goldschmidt said of LeBlanc. "His changeup is really good, and I know he doesn't throw hard, but he pitches inside and he jams a lot of guys for a guy who throws 89-90 mph. He does a good job. I always thought highly of him last year when I faced him."
On Tuesday, the Marlins rallied to a 6-5 win after Ricky Nolasco gave up five in the first. And in Game 1 on Wednesday, Turner allowed a two-run homer to Aaron Hill in the first inning.
Goldschmidt hurt LeBlanc again in a two-run fourth. Hill walked to open the inning, and Goldschmidt doubled. With one out, Chris Johnson delivered an RBI single. LeBlanc put himself in position to get out of the jam by striking out Wil Nieves. John McDonald was intentionally walked to get to Miley.
With Miley at the plate, Rob Brantly's second passed ball of the inning scored Goldschmidt to give Arizona a three-run lead.
"That's the first time that he's caught me," LeBlanc said of the rookie. "I have a lot of different things that I do as far as sequencing that it's probably not the easiest thing to catch onto in the first start. But he did a good job getting on the same page as I was."
Brantly was making his fifth start since being called up from Triple-A. The 23-year-old, acquired from the Tigers along with Turner in the Anibal Sanchez/Omar Infante deal, is expected to go through some growing pains.
"That's going come with it," Guillen said. "Obviously, it wasn't too pretty behind the plate. We've got to help him. We've got to get him a lot of confidence. We know with him coming here, that's what we're going to deal with. It's not the kid's fault.
"We want to see him. Hopefully, with more playing time, he gets more relaxed. I think he needs to relax a little bit more. I think he's a little bit tense, anxious. I think in the big leagues, you've got to try to make this game slow down a little bit for you. That's a process. We've got to tame him."