SAN FRANCISCO — Jay Bruce held his batting helmet to his face, hoping that it would muffle his screams. However, the sound mattered far less than the image, which flickered across television screens, a distress signal for a beleaguered fan base.

Bruce had arrived at a time of hope, when anything seemed possible, even a turnaround of a season warped by fragile bones and the inherent cruelty of baseball’s ebb and flow. Now there are only signs that these Mets may be past the point of salvation.

“As a major-league baseball player, I really, truly believe I can make an impact. I have for a long time,” said Bruce, whose double-play groundout in the eighth inning marked the Mets’ final chance to alter the course of an 8-1 loss to the Giants on Friday night.

In his 16-game Mets tenure, Bruce has blended into the malaise. Traded from the Reds at the deadline, partly for his ability to knock in runners, Bruce is hitting .176, mired in territory for the inconsequential.

For weeks, the Mets have been locked in a gray area, their postseason aspirations muddled in uncertainty. They have played poorly, yet they have remained on the fringes of contention. Baseball’s second wild card has made dreamers out of pretenders.

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But every day, the line becomes clearer and clearer. And when they awaken on Saturday morning, the Mets will encounter a host of unflattering realities. They have dropped four of five on their 10-game road trip, fallen to two games below the .500 mark (60-62) and tumbled to 5 1⁄2 games behind the Cardinals, who own the final playoff spot in the National League.

“When you go through bad stretches, it is everything,” said manager Terry Collins, whose team has lost 16 of its last 23 games. “There’s no one territory. It’s everything.”

For nine innings, the Mets ran through a checklist of failures and dutifully crossed off each one. They ran the bases carelessly and failed to grasp the basics of fielding. The bullpen, burned out and exhausted, allowed a close game to morph into a rout. And almost out of obligation, the Mets performed their signature act, failing to deliver with runners in scoring position.

Said Collins: “It seems like a lot of nights, we’re talking about somebody who’s not hitting with guys on.”

It didn’t begin that way, though.

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Rookie Seth Lugo defied expectations, pitching into the seventh after being pressed into spot starting duty because of Steven Matz’s shoulder injury. He was pulled after 69 pitches, with Collins content that he’d gotten all he could ask from the righty making his first big-league start.

“I just wanted to fill up the strike zone, so I was happy with that,” said Lugo, who survived a hail of hard hits.

He departed with the score tied and two on for lefty reliever Jerry Blevins, who has made a habit of stranding inherited runners. But Ehire Adrianza delivered a pinch-hit double to give the Giants the lead for good and Denard Span followed with a single for an insurance run.

Soon, the rout was on. The Giants ripped apart the Mets’ bullpen, tacking on seven runs in the final two innings. By then, the Mets had long blown their best chances to sway the outcome.

Asdrubal Cabrera, fresh off the disabled list, let a routine pop-up fall to the ground, then made a throwing error that allowed the Giants to pile on. Yoenis Cespedes, in his first game back from a strained quadriceps, collected his only hit with the game out of hand. He was wiped out on a baserunning gaffe.

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For the Mets, it wasn’t the first.

Poor baserunning wiped out a potential rally in the fifth, with the score tied 1-1 after Curtis Granderson’s solo shot into the waters of McCovey Cove in the second.

With runners on first and second, Kelly Johnson poked a single to right. But running from second base, Lugo looked down to touch third base, missing a stop sign from third-base coach Tim Teufel.

“I don’t run the bases very often,” said Lugo, who rounded third base.

Noticing this, Jose Reyes motored hard around second base, winding up more than halfway to third. When the slow-footed Lugo caught himself and returned to third, he had no choice but to get into a rundown.

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Still, the Mets trailed just 3-1 in the top of the eighth. With one out, Reyes lashed a single, his fourth hit of the night. Giants first baseman Brandon Belt gave the Mets a gift, plunking Reyes in the back with a throw to second after fielding Johnson’s grounder.

Up came Bruce, in precisely the situation in which the Mets need him to thrive. He mustered only a grounder to first, the start of an inning-ending double play.

Overcome by frustration, Bruce retreated to the dugout, then vented into his helmet. Soon, he would hear from his manager. With his team in a tailspin, Collins decided that the Mets cannot afford to play Bruce.

“He’s really pressing,” Collins said. “He’s trying to do some things. It comes with the territory when you’re a star. You come to a new team. You want to do everything you can to help. I told him I’m giving him tomorrow off.”