The slumping d'Arnaud had an RBI single with two outs 12th inning and Black earned his first career win in New York's 1-0 victory over the Miami Marlins on Sunday.
"It's big. Extra-inning game, bases loaded, and just get that hit. It's an undescribable feeling," d'Arnaud said of his first walkoff hit in the major leagues. "More importantly it was a big win (to win) the series. Try to lead the Mets in the right direction."
With several rookies' families in town, d'Arnaud gave the game ball right to his mom. Black was given the lineup card, and it was sitting in his locker. He said it will be going home to Texas with his parents.
Dillon Gee and Tom Koehler took a pitchers' duel into the eighth inning before the Marlins and Mets each used five relievers to finish off the fifth extra-inning matchup this season between the NL East's worst teams.
D'Arnaud came through in a game of many missed opportunities and after the two previous batters grounded into forceouts at the plate. New York had loaded the bases with no outs against Zach Phillip (0-1), making his third appearance for the Marlins.
Ryan Webb relieved after Lucas Duda walked to load the bases and got pinch-hitter Zach Lutz to ground to third base. Andrew Brown then grounded to first base, and the throw went home for the second out.
"I think guys sometimes in that situation they just relax because, 'Hey, we've got our backs against the wall already,' and he made some great pitches," Miami manager Mike Redmond said. "It looked like he was going to get through the inning."
D'Arnaud, who singled in the 11th only to be stranded at third base, lined a soft single up the middle to give the Mets their fifth win in 16 home games. Acquired by New York in the offseason trade that sent NL Cy Young Award winner R.A. Dickey to Toronto, has just five hits in his last 28 at-bats.
"It's about the process itself," Mets manager Terry Collins said of the Mets hitting. "And that's why you see good at-bats, you see them work the count, you see them taking a better swing, you see them starting to use the two-strike approach."
Black (1-0) pitched a perfect 12th inning, his 12th appearance between Pittsburgh and New York this year.
Miami wasted chances early, going 0 for 12 with runners in scoring position in the first nine innings. Eric Young Jr. was the only Mets player to reach second base -- a two-out double in the sixth -- until they put a runner on third in the 11th. But Young was struck out by Chad Qualls to end the threat.
"We had lots of opportunities, again," Redmond said. "They gave us a couple opportunities in the ninth, two errors, and we just weren't able to capitalize."
The Marlins have lost eight of 10.
Gee and Koehler had batters flummoxed into the eighth. Both mixed breaking balls that dipped into the 70s with a fastball that reached 90 mph for Gee and 94 mph for Koehler. The result: flailing bats, awkward checked swings and a whole lot of softly hit balls.
"Obviously Gee's a real quality starter, and you want to limit as much as you can as far as hits and runs," Koehler said. "But no matter who you're facing you've got to put up zeroes until you win."
The Bronx-born Koehler was 0-4 with a 5.89 ERA in seven starts since beating the Mets since Aug. 1 with six scoreless innings.
Pitching in front of more than 40 friends and family from the area -- he grew up in New Rochelle and played college ball at Stony Brook -- he was impressive against a team that had scored just 12 runs in the first seven games of a homestand.
Gee sent a soft line drive over a ducking Koehler's head with two outs in the third for the Mets only baserunner before Young doubled.
Koehler allowed three hits in a career best-matching eight innings. He struck out five without walking a batter -- he had gone six straight starts giving up at least two walks.
Gee has been stingy when he has allowed runners on base. Batters were just 3 of 28 with runners in scoring position coming and the Marlins were worse: hitless in seven at-bats against the right-hander.
Gee gave up six hits in 7 1/3 innings. He walked two and struck out eight, including four in a row between the second and third.
Murphy made two errors in the ninth, ending the Mets' season-high eight-game errorless stretch. ... Collins said reliever Frank Francisco will be unavailable for several days after he was hit on the right hand by a line drive in the opener of Saturday's doubleheader. ... The Marlins are 5-13 in extra innings. The Mets are 8-10.
Copyright by STATS LLC and The Associated Press
NEW YORK, NY - SEPTEMBER 15: Tom Koehler #34 of the Miami Marlins pitcheds in the first inning against the New...