SAN FRANCISCO — The contrast in catchers couldn’t have been much starker. Buster Posey hit the go-ahead homer for the Giants on Friday, and Travis d’Arnaud was an instant rally killer for the Mets.
In a season that is heading due south for the Mets, their once-heralded catching prospect d’Arnaud is sinking even faster.
With Posey’s two-run homer in the eighth inning against Carlos Torres as the difference, the Mets lost their fourth straight, 4-2 before 41,437 at AT&T Park.
The Mets (28-33) fell to 4-5 on a road trip that began with four victories in five games in Philadelphia before the hapless Cubs swept them three games at Wrigley Field.
D’Arnaud finished 0-for-3 and hit into two double plays on a night the Mets managed just four hits against Matt Cain and two relievers.
Since returning from a concussion, d’Arnaud is 3-for-26 (.115). Overall, he is batting .180 this season.
“I’ve got to be better than this,” d’Arnaud said. “This is unacceptable for me.”
The rookie’s struggles have tested manager Terry Collins’ resolve, especially with the rest of the Mets lineup struggling to produce with runners on base.
“That’s the age-old question that every manager that has young players and rookie players has to deal with, and that’s when they go through real tough times, how do you keep their spirits up?” Collins said.
“None of us have the answer that is universal, but he’s a confident kid and he certainly believes he’s going to hit, because he always has. But there are some things he has to do to be able to start hitting at this level.”
D’Arnaud’s second double play of the game, after Ruben Tejada had delivered a one-out single in the eighth, was a crusher.
In the bottom of the inning, the former MVP Posey homered into the left-field seats against Torres to put the Giants ahead.
Jon Niese rolled into the seventh and got two quick outs before Brandon Hicks walked and advanced to second on a wild pitch. Brandon Crawford’s ensuing RBI single made it 2-2.
The lefty Niese went seven innings and allowed two earned runs on five hits with three strikeouts and a walk in taking the no-decision.
“Unfortunately we had the lead there in the seventh, and I made that mistake,” Niese said. “It should have been a different ballgame.”
Daniel Murphy’s two-run homer in the seventh brought the Mets to life after they sleepwalked through the first six innings. Matt den Dekker doubled leading off the seventh against Cain and Murphy followed with a shot into the right-field seats for his fourth homer, giving the Mets a 2-1 lead.
The Mets didn’t get their first hit until the sixth, when Tejada singled leading off, but that momentum was quickly erased when d’Arnaud hit into a double play.
Hicks’ triple in the fifth led to the Giants taking a 1-0 lead against Niese. The next batter, Crawford, hit a fly to medium left field, and Andrew Brown’s throw home hit Hicks as he slid into the plate.
Cain was making his first start since May 21 after missing the last two weeks with a right hamstring strain. The right-hander lasted seven innings in which he allowed two earned runs on three hits with one walk and three strikeouts.
After Cain retired the first 12 batters, Curtis Granderson walked leading off the fifth. Granderson, who entered tied for eighth in the NL with 32 walks, has reached base in each of his last 19 games.
But the Mets couldn’t get any traction: Brown hit into a double play before Lucas Duda was retired, allowing Cain to take his no-hit bid into the sixth.
Niese allowed a leadoff single to Posey in the fourth, but got Michael Morse to hit a grounder that Tejada turned into a 6-6-3 double play that ended the inning.