NEW YORK -- Back home from a frustrating road trip, the New York Mets immediately busted out of their offensive funk against the worst team in the majors.

Amed Rosario hit a grand slam during an eight-run outburst that marked the Mets' biggest first inning in three decades, and New York rolled to an 11-2 rout of the Miami Marlins on Friday night.

"It was great. It was a lot of fun to kind of break out as a team," Michael Conforto said. "It's something we've been waiting for."

Conforto and Jeff McNeil also homered for the previously slumping Mets, who set a season best with 15 hits and matched their high for runs. Zack Wheeler (3-2) struck out 11 over seven innings, reaching double digits for the third time in four outings.

Earlier in the day, manager Mickey Callaway met with Mets chief operating officer Jeff Wilpon and general manager Brodie Van Wagenen.

"This meeting had a different focus. This meeting was about, how can we be better? How can we get going in the right direction?" Callaway said. "None of us are satisfied with what's been going on to this point.

"We talked about a lot and we understand that things have to be better."

Right off the bat, they were.

After totaling only 15 runs during a 1-5 trip to Milwaukee and San Diego, the Mets broke loose against Pablo Lopez (2-5) and the Marlins (10-28). New York sent 13 batters to the plate in the first, with J.D. Davis and Robinson Cano each getting two of the team's eight hits.

The first run scored on Lopez's wild pitch. Slow-footed Wilson Ramos legged out a dribbler up the third-base line for an RBI single, and Brandon Nimmo drew a bases-loaded walk.

Rosario, batting eighth, sent the next pitch just over the right-center fence for his first major league slam -- instantly giving him a career-high four RBIs.

Wheeler struck out, making him the first batter retired by Lopez. But when Cano added a two-out RBI single, the Mets (18-20) had their largest first inning since they also scored eight times at Philadelphia on June 16, 1989.

"You don't see that type of inning very often," Callaway said. "I think everybody took a deep breath after that. Like, OK, we can still score runs."

The inning could have been even worse for Lopez, too, if right fielder Brian Anderson hadn't wheeled around to make a spectacular throw that nabbed McNeil trying to go first to third on Davis' single for the first out.

McNeil led off with a bunt single, diving into first to evade a tag, and reached safely four times. Conforto was 3-for-3 with three runs and reached safely all five times up. Davis finished with three hits.

"Now is as good a time as any time to start making our move," Conforto said. "We're going to put it all together here very soon."

Conforto homered into the right-field upper deck leading off the second. McNeil connected in the third against the 23-year-old Lopez, who was coming off six shutout innings against Atlanta and had not allowed an earned run in two of his previous three starts.

"Didn't look like he had life on his fastball. Didn't look like he was locating very well. Things got snowballing and usually that's tough," Miami manager Don Mattingly said. "So, it was one of those nights."

Lopez, who beat Mets ace Jacob deGrom 5-2 in his major league debut June 30 last year, gave up 10 runs and 10 hits over three innings, easily the worst of his 18 career starts.

"Everything happened very quick. I kept falling behind," Lopez said. "You can only get better after this."

BEEN A WHILE

The Mets scored more runs in the first inning than they had during an entire game since a 9-0 win over the Phillies on April 23. New York mustered only 16 runs over its previous eight games -- one of which went 18 innings.

The only other time in franchise history they hung a snowman in the first at home was July 12, 1979, against the Dodgers. The club record is nine first-inning runs at San Francisco in August 1988.

TRAINER'S ROOM

Marlins: 1B-OF Garrett Cooper (bruised left hand) is moving from Class A Jupiter to Triple-A New Orleans on his rehab assignment. ... RHP Julian Fernandez (Tommy John surgery) is scheduled to throw 20 pitches of live batting practice Saturday.

Mets: The team decided against activating veteran infielder Jed Lowrie from the injured list Friday, as originally anticipated. Lowrie got hurt early in spring training and has been sidelined all season because of a capsule sprain in his left knee. He was 1-for-7 with Class A St. Lucie and 1-for-16 at Triple-A Syracuse during the first six games of his rehab assignment. Callaway said the Mets planned to re-evaluate Saturday. Lowrie went 3-for-4 with a home run and a walk Friday night for Syracuse. He played nine innings at third base. ... LHP Steven Matz is slated to throw a bullpen Saturday, an important step after he received an injection of cortisone and lidocaine for his aching left forearm early this week. Matz was placed on the 10-day injured list Thursday, retroactive to May 5, with radial nerve discomfort, and the Mets hope he can return to the rotation next week.

UP NEXT

Marlins: Sandy Alcantara (1-3, 4.93 ERA) pitches Saturday night, his fourth assignment against the Mets in 14 major league starts. The 23-year-old right-hander is 0-3 in his last five outings overall.

Mets: National League Cy Young Award winner deGrom (2-4, 3.60 ERA) has lost four straight decisions, and New York hasn't scored in either of his past two games. In his second outing this season, deGrom struck out a career-high 14 over seven shutout innings at Miami. Still, he is just 5-6 with a 3.36 ERA in 17 starts against the Marlins.