PHOENIX -- Matt Harvey gave the New York Mets a chance to win. But the end result was all the same.

Harvey kept the Mets ahead into the sixth inning. But the Arizona Diamondbacks' Chris Herrmann belted a walk-off home run to center field in the 11th inning to give the D-backs a 5-4 win Wednesday afternoon and send the Mets to their seventh straight loss.

Herrmann's shot, his first career walk-off homer, came on a 3-2 pitch from Rafael Montero (0-3).

Harvey threw 5 1/3 innings, giving up three runs and six hits. He walked four and struck out six.

"Probably the best I've felt in two years," said Harvey, who studied video of his performances in 2013 and 2015 and a recent bullpen session. That, he said, allowed him to return to a more natural, lower arm slot.

Harvey said he picked up a "lot of bad habits" because he couldn't throw from his preferred angle without getting "tingling and numbness in my index finger."

"I'm close to where I want to be," he said.

But this was the only solace for the Mets, whose bullpen now has allowed eight homers in their last eight games.

"It's very easy to unravel right now," Mets manager Terry Collins said. "I will not let that happen here. We are not going to do that.

"We are going to stay together, play together. I will not let this team get down."

While acknowledging, "Losing can be as contagious as winning," Collins said, "We're going to turn this around."

By winning, the D-backs (24-18) moved to a season-best-tying six games over .500.

"It's awesome, man," said Herrmann. "I haven't hit very many homers in my career. I hit a grand slam, but I don't think there's anything that compares to hitting a walk-off home run. It's something you dream about when you're a little kid, whenever I'm 6 years old, playing out in the cul-de-sac, hitting tennis balls."

As a catcher, Herrmann said, "Honestly, playing extra innings suck. I'm pretty happy I was the one to do it. You get tired behind the plate, and my knees were starting to hurt a little bit.

"I just told myself to take a nice, easy swing and put the ball into play. And I hit it out of the park."

For the Mets, Wilmer Flores went 3-for-5 while Jose Reyes went 3-for-6.

Michael Conforto gave the Mets an early lead by hitting a two-run homer in the first. Juan Lagares hit a solo homer.

Harvey left with the Mets leading 4-3. Then Arizona's Yasmany Tomas doubled home Paul Goldschmidt, who had walked, to tie the game, 4-4, in the seventh.

"At that point, we felt very good about our chances," D-backs manager Torey Lovullo said.

For the Diamondbacks, Patrick Corbin gave up four runs and nine hits in six innings. He walked one and struck out six.

Neither starter figured in the decision.

Also for the Diamondbacks, Jake Lamb hit a two-run homer and drew two walks. Relievers Andrew Chafin, J.J. Hoover, Fernando Rodney and Jorge De la Rosa combined for four scoreless innings, while allowing just two hits.

"They've been huge pretty much all year," Corbin said. "Our offense is going to score, eventually, so if they keep doing that, we're going to win a lot of these games."

With two outs in the top if the 11th, Tom Wilhelmsen (1-1) walked Matt Reynolds and Lucas Duda, but struck out Reyes to end the threat.

The Diamondbacks closed out their nine-game homestand at 6-3, including the three-game sweep of the Mets.

NOTES: Both teams will enjoy an off day on Thursday. After that the Mets will play a six-game homestand against the Los Angeles Angels and San Diego. By contrast, the Diamondbacks will play 17 straight days, with 14 of them on the road. Manager Torey Lovullo said this stretch "will define a little bit of who we are. Certain parts of the schedule that jump out at you. That was one." The D-backs will first play at San Diego, a team they've already played seven times (4-3) this season.... Mets LHP Steven Matz is scheduled to pitch for Class A St. Lucie Thursday. He has been on the disabled list since the start of the year with left elbow inflammation.... Mets RHP Seth Lugo is scheduled to pitch Thursday for Class A St. Lucie. He also has been on the DL since the start of the year with right elbow inflammation.