Making his first start, and second Grapefruit League appearance, the 22-year-old former first-round pick walked five and hit a batter in three innings against the Red Sox.
The fourth largest crowd to watch the Marlins in Jupiter, 8,151, saw Florida prevail, 3-2, over the defending World Series champions.
Miller, who didn't factor into the decision, gave up one run. He struggled to find the plate, as 23 of his 53 pitches were strikes.
Afterwards, Miller acknowledged that his delivery is a bit off the mark.
"When you get a little wild, how soon can you get out of it? It took me, obviously, way too long today," said Miller, whom last year, in 13 starts with the Tigers, struck out 56 and walked 39 in 64 innings. "I felt I was guiding it a little too much. You live and you learn, and next time you try not to do too much."
Miller's struggles with control started off from the first pitch of the game, when he plunked Jacoby Ellsbury with a fastball.
Miller faults himself for even using that baseball. He said he warmed up with that ball, and found it a bit slick. But instead of swapping the ball out before the game started, he went with it, and the result was an immediate baserunner.
In a wide open rotation battle, Miller is one of many fighting for a spot on the Opening Day roster. Obtained in the trade from Detroit for Dontrelle Willis and Miguel Cabrera, Miller is viewed as a future top of the rotation candidate.
Right now, however, he understands that nothing is guaranteed, and he has to show he belongs.
Still, his talents are obvious to catcher Matt Treanor.
"For me, I thought he was still impressive," Treanor said. "This was my first time catching him in game action, and you can definitely see why we picked him up. He's a great talent, and he's got a lot of upside to him."
Maybin improving: Cameron Maybin took a big step toward returning from his stiff left hamstring.
On Monday, the 20-year-old center fielder did some light jogging for the first time since tweaking his left hamstring last Friday against the Nationals in Viera.
"It feels good," Maybin said. "It's a lot better than two or three days ago."
There still is no rushing the highly-touted outfield prospect.
Maybin is competing for the starting center-field job with Cody Ross and Alejandro De Aza.
The team is taking things slowly with Maybin, who projects to be a big part of their future. For now, he's been giving the hamstring ice and heat treatment.
Since Saturday, he's been riding a stationary bicycle as well.
"Maybin is doing a little bit more," manager Fredi Gonzalez said. "He was doing some extra running, and agility stuff. Maybe [he will be back by] the end of this week."
McPherson returns: For the first time this spring, Dallas McPherson was in the lineup. Bothered the past few days with a tight oblique muscle, the left-handed hitting third baseman was eased into action as a designated hitter.
The former product of the Angels, McPherson likely will see his first action in the field on Tuesday.
McPherson, who was hitless in two at-bats on Monday, is in the mix for the starting third-base spot, which at this point appears to be Jose Castillo's job to lose.
Castillo, McPherson and Jorge Cantu are getting the majority of work at third base.
Gonzalez said McPherson and Cantu will each see time in the upcoming days at first base.
Later on in Spring Training, outfielder Luis Gonzalez also should field some grounders at first base.
Patterson possibility? Barring a change of plans, the Marlins are not expected to make a serious run at signing center fielder Corey Patterson.
There have been reports that Florida would pursue Patterson as a fallback plan if Maybin isn't ready to secure the starting job by Opening Day.
Patterson, who played last year for the Orioles, right now is not regarded as an alternative, as the team is still leaning toward letting Maybin, Ross and De Aza compete for the job.
Mitre update: Either Wednesday or Thursday, Sergio Mitre will resume throwing.
Last Friday at Fort Lauderdale against the Orioles, Mitre made his first Grapefruit League start. It lasted 15 pitches before he was removed with tightness in his right elbow.
Mitre will throw off flat ground, starting off at 60 feet.
Birthday blast: On his 32nd birthday, Treanor celebrated with a home run in the fifth inning.
"A couple of guys came up and told me that was pretty nice to do on my birthday," said the catcher, who has gone deep six times in his Major League career.
One thing Treanor does when he goes deep is he sprints around the bases. He was taught that in high school as a way of not trying to show a pitcher up.
"That was a big solo home run," Gonzalez said. "Did anyone put a clock on him going around the bases?"
Coming up: On Tuesday, the Mets visit Jupiter to take on the Marlins. Florida is going with lefty Mark Hendrickson (0-0, 4.50), while New York is starting John Maine (0-1, 16.20). First pitch is at 1:05 p.m. ET.
Joe Frisaro is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.