SAN FRANCISCO -- The Giants' offense showed few signs of life for most of Monday night against the Mariners. After an overnight flight home from New York, the team arrived back in the Bay Area well after 3 a.m., and the result was a sluggish, three-hit performance through the first eight innings. Despite three runs in a ninth-inning rally, the last-minute effort was not enough as the Giants fell, 6-5, in their series opener with Seattle.

San Francisco has now lost six of its last eight, and with injuries accumulating, the Giants have hit a skid as they near the All-Star break. The mounting concerns were worsened by the announcement that Thairo Estrada was placed on the 10-day injured list with a left hand fracture suffered when he was hit by an Adam Ottavino pitch on Sunday against the Mets. After Monday's game, manager Gabe Kapler said the Giants expect Estrada to be out for 4-6 weeks, though they are still in the “information gathering stage” and are unsure whether surgery will be required.

“The pitch hit me hard. I feel that if [Ottavino] hadn’t hit my protector, the injury would have been worse,” said Estrada through interpreter Erwin Higueros. “The [medical staff] are saying four to six weeks, so hopefully everything goes well. I’m a very positive person, so I believe in them.”

With the loss of Estrada, the Giants will be without their third-highest WAR contributor at 2.3. On the season, Estrada has a .761 OPS and 31 RBIs in 70 games.

Recently, it’s been more of a team-wide slump, most pronounced when it comes to scoring opportunities. After hitting just .190 with runners in scoring position in the last seven games, the Giants started the first eight innings Monday going just 1-for-7 in those situations. While Mike Yastrzemski and Michael Conforto returned to the starting lineup and Brandon Crawford made a late-inning appearance after a hard diving play the previous day, the sense is that the Giants are fatigued after a tough East Coast swing. Right-hander Anthony DeSclafani was also added to the 15-day IL with ongoing right shoulder fatigue.

Despite the struggles, the game was tied, 2-2, heading into the ninth, when newly minted All-Star Camilo Doval came in to try to keep it tied. Instead, he was rocked for four earned runs, the most he’s given up in any career appearance. Working with rookie Blake Sabol behind the plate, Doval hit a batter, uncorked a wild pitch and allowed three stolen bases.

“One thing to remember is that Camilo is an All-Star and one of the better closers around baseball, that’s abundantly clear,” said Kapler. “He also has a little bit of work to do in terms of slowing things down, remembering that he’s controlling the run game. Tonight, it just wasn’t there for him.”

All of the Giants' scoring came off the bat of Sabol, who had two homers and a career-best five RBIs -- a two-run blast to give the Giants the lead in the fourth and a three-run shot in the ninth that put the Giants within one. It was his first career multi-homer game, and the inspiration for the big evening may have come from Barry Bonds himself.

“I actually got my first hitting lesson with Barry today, and so maybe he knows a thing or two about hitting some homers. He had me stand up with my posture, and it freed up my body a little bit,” said Sabol. “That was probably the best I’ve felt since Spring Training, as far as how free my body felt turning and how still my head was.”

Overshadowed by the injury news and late-inning drama was a solid rebound start by Logan Webb. The Giants needed Webb to eat innings after six innings of bullpen work on Sunday, and the righty did his part, tallying 11 strikeouts while allowing two earned runs over 6 2/3 innings.

“I thought Logan looked disgusting,” said Sabol. “His slider was mean, and I was telling him, ‘Your slider is stupid.’”

In eight starts at Oracle Park this year, Webb has earned a quality start each time, with an ERA of 2.36 at home. As for the slider, Webb earned 15 called strikes and whiffs on 31 offerings.

“The slider was better than it has been lately,” Webb said. “It was a good pitch to get ahead and with two strikes, which was a positive sign.”

Despite the strong outing from Webb, the Giants are now in the middle of their roughest stretch since mid April. And with a new bout of injuries, they’ll need to dig deep to turn things around with five games to go until a break that’s feeling increasingly necessary.