PHOENIX — Francisco Alvarez’s June swoon mirrored the Mets’ overall play, but suddenly the rookie catcher is eliciting oohs and ahhs from the crowd again, propping up his team along with him.

With the Mets embroiled in a back-and-forth slugfest with the NL West leaders on Tuesday it was Alvarez who created the loudest Fourth-of-July crackle with a go-ahead homer in the seventh that propelled an 8-5 victory over the Diamondbacks at Chase Field.

The Mets won their third straight — something they last accomplished on June 1 when they completed a sweep of the Phillies — and Alvarez has homered in two of those victories.

On this day he came to the plate in a 4-4 game in the seventh and blasted a 467-foot rocket that left the bat at 110 mph for a two-run homer.

The Mets were ahead for the remainder of the game.

“Once you see the ball going that far your emotions start to heighten there, because you know the significance of that moment,” Alvarez said through an interpreter.

Alvarez’s early July thunder has followed a June in which he produced only a .534 OPS after a breakout May.

“I think I am slowly but surely getting back there,” Alvarez said. “I don’t think I am back to the same level that I was that month I was playing really well, but I think I am getting there.”

Buck Showalter certainly values Alvarez’s offense, but says his continued development behind the plate takes precedence.

“He’s a 21-year-old catcher making adjustments on the fly,” Showalter said. “He’s seeing things and growing from them little by little. I’m just happy with the way he’s catching. I think more than anything the other stuff will just be a plus and put him on a different level if he can do that.”

The Mets (39-46) still need plenty of victories before they can rightfully consider adding significantly at the trade deadline, but the last three games have at least provided a shred of hope.

Brooks Raley, Adam Ottavino, Drew Smith and David Robertson combined to pitch the final three innings, stabilizing the Mets following Max Scherzer’s shaky performance.

Smith allowed two base runners in the ninth, prompting Showalter to utilize Robertson for the final out.

Scherzer survived six innings, allowing four earned runs on five hits with two walks and nine strikeouts.

The Mets co-ace matched a season high by surrendering three homers, in his worst start of his last four. Scherzer had pitched to a 2.25 ERA over his previous three starts to resurrect his season, which was spiraling toward the abyss.

Corbin Carroll’s homer in the first inning gave the D’backs a 1-0 lead.

The homer was Carroll’s 18th this season, a continuation of the torrid play that has placed him as the front-runner in the National League Rookie of the Year race.

Starling Marte’s three-run homer in the fourth put the Mets ahead 3-1.

Francisco Lindor walked and stole second to begin the rally and Jeff McNeil’s two-out infield single kept the inning alive. Marte — who began the day 12-for-31 (.387) lifetime against D’backs starter Zach Davies — hit a no-doubter into the left-field seats for his fifth homer of the season.

Scherzer recorded two fast outs in the fourth before Christian Walker and Lourdes Gurriel Jr. launched consecutive homers that tied it 3-3.

Brandon Nimmo continued his power surge with a homer in the fifth that gave the Mets a 4-3 lead.

The homer was Nimmo’s ninth in his last 23 games and 13th overall. Five of Nimmo’s homers have come in his last eight games.

Davies had retired Alvarez and Brett Baty to begin the inning before Nimmo hit a line drive that cleared the right-field fence.

The D’backs got the run back in the fifth, but it could have been much worse for Scherzer, who struck out Walker with the bases loaded to end the threat.

The previous batter, Carroll, walked with the bases loaded to tie it 4-4 after two infield hits and a walk began the two-out rally against Scherzer, who needed 32 pitches in the inning.

Alvarez’s homer in the seventh that put the Mets ahead 6-4 after Daniel Vogelbach had walked to put the go-ahead run on base.

The Mets extended their lead in the eighth by loading the bases before D.J. Stewart’s sacrifice fly brought in Lindor. In the ninth Lindor stroked an RBI double for the Mets’ final run.

“The mindset is we have got to continue to play well and continue to win,” Scherzer said. “Everybody has got to do their job across the team to get wins. Today is a perfect example. It took a total team effort and was a total team win.”