Then, when Garrett Jones capped off the scoring with a two-run homer in the ninth, his 25th, this trio joined 1966's Willie Stargell (33), Roberto Clemente (29) and Donn Clendenon (28) as the only 25-plus threesomes in team history.
That's a lot of home runs -- and a lot of history.
"And it's not like a bunch of older guys are doing it, or guys on the backside of their careers," noted Pirates manager Clint Hurdle. "Those are things you like to have when building a ballclub."
Then there's McCutchen, who went 1-for-3 -- he also drew two of the Bucs' seven walks -- as he tries to nail down Pittsburgh's 26th National League batting title.
Oh, and with the win, the Bucs staved off postseason elimination, although the next time they lose or the Cardinals win, it will officially be "wait till next year" time.
Alvarez's opposite-field shot also was the Pirates' 100th on the road, tying the Los Angeles Angels for most in the Majors, a knot undone eight innings later by Jones.
But the coolest thing for Alvarez, who wound up driving in a total of four runs, was finally hitting his first home run near his New York City roots, in front of family and friends.
"To be able to do it in front of all the support, in a Major League park in the city where I grew up ... really, a dream come true," said Alvarez.
Meanwhile, Grilli's eighth-inning strikeout of Ike Davis established a new club record, breaking the mark of 1,124 set by the 1969 Bucs.
"It's cool, a good little feather in the cap to have," Grilli said. "We all contributed to that, for sure."
Grilli was the third of four relievers to pick up Wandy Rodriguez, who made a remarkable recovery from a very shaky first inning to go six innings for his 12th win and improve his record with the Pirates to 5-4. Joel Hanrahan finished up in the ninth.
Hurdle, who explicitly wanted to assemble a staff that pitched less to contact than his 2011 outfit, took greater pleasure in the strikeout feat. Besides, 30-30 homer men do not as much impress Hurdle, who saw quite a few of them in his seven-plus seasons as Rockies manager.
Threatened with being the victims for the first Major League wins of two rookie right-handers on consecutive nights, the Pirates demurred loudly against Collin McHugh. On Monday night, Jenrry Mejia had blanked them for five innings for his No. 1. McHugh wasn't allowed to get out of the second, being charged with seven runs in 1 1/3 innings.
Even Hurdle finally won one. An argument, that is: Justin Turner reached in the third when his grounder to second was muffed by Josh Harrison, who nonetheless unfurled a wild throw past first. Rod Barajas backed up the throw and first baseman Gaby Sanchez, seeing Turner slightly pivot toward second base, urged the catcher to throw him the ball and with it tagged Turner.
First-base umpire Phil Cuzzi signaled Turner safe. When Hurdle came out to plead his case, Cuzzi consented to consult the other umpires -- resulting in Turner being called out.
"We had a very candid conversation," Hurdle said of his huddle with the umpire, "and based on the information I shared, [Cuzzi] was compelled to at least ask for some help. Because there was no doubt that [Turner] had made a move in the other direction."
After the Pirates had given Rodriguez a 4-0 lead in the top of the first, the bottom turned into a first of "firsts" for the Mets. After a leadoff single by Ruben Tejada, Turner got his first hit since Sept. 5 and his second homer of the season -- in 162 at-bats. David Wright followed that with his 20th -- the Mets' very first instance of back-to-back homers this season, trimming the lead to 4-3.
All that had taken 45 pitches out of Rodriguez -- the most in one inning by any Pittsburgh pitcher this season, according to Hurdle.
In a forgiving mood, the Pirates gave Rodriguez another four-run lead in the second, while chasing McHugh. Harrison's two-run triple and Jones' RBI grounder made it 7-3.
Rodriguez showed his appreciation by blanking the Mets on one hit for the rest of his stint. He walked two and struck out three, including Scott Hairston for the record-tying No. 1,124 in the third.
"A very impressive performance," Hurdle had to conclude of the entirety of his lefty's evening. "I actually had a reliever up in the first, because of the pitch count. He was trying to shave the ball on both sides, and unfortunately it was cutting back into the middle of the plate.
"Then he went from the two- to the four-seamer and the breaking ball. It was dramatic ... to be that close to being taken out of the game. He just kept getting better. Needed only nine pitches in his final inning, the sixth. Very proud of him."
"It was simply my location," Rodriguez said of the stressful first. "I missed with a lot of pitches. I was trying to hit the corners, and the ball would go right down the middle, and they hit it well. I went back to work thinking, 'I can put the ball wherever I want,' and concentrated on that."
The Mets tightened up the game in the seventh with three runs off the Pittsburgh bullpen, two of them scoring on Wright's single off Jared Hughes. That two-run single was hit No. 1,418 for Wright, tying Ed Kranepool's Mets record.