SAN DIEGO — In the middle innings of a tight game, the Red Sox all of a sudden found themselves on the highway to the danger zone Saturday night, stuck facing the Padres’ so-called super-bullpen.
The Sox actually held a lead in an eventual 5-4, 10-inning loss when San Diego began to turn to its top guns. But even after innings of domination yielded to a fleeting breakdown — Roman Anthony’s tying double off closer Robert Suarez in the ninth — the opposing relief corps was just too good.
Against the Padres’ sixth reliever of the game, All-Star lefthander Jason Adam, possessor of a 1.75 ERA, the Red Sox failed to advance their freebie extra-inning runner past his starting point of second base. In the bottom of the 10th, Garrett Whitlock threw one pitch, to Ramón Laureano, who chopped it over third baseman Alex Bregman and into left field for a walkoff single, scoring Xander Bogaerts.
The Red Sox (65-53) totaled 13 strikeouts and one run in the final six innings against Jeremiah Estrada, Adrian Morejon, Mason Miller, Suarez, and Adam.
“It’s the best bullpen in the big leagues,” manager Alex Cora said. “It’s amazing. They did a good job adding people [at the trade deadline] and they’ve been really good throughout.”
The Sox’ relievers were good, too, Cora noted. And that was true. Steven Matz, Jordan Hicks, Aroldis Chapman, and Whitlock held the Padres (65-52) to two hits in 4⅓ innings.
The difference came in the 10th. An awkward moment, leading off the top of the final frame: David Hamilton, who had entered as a pinch runner for Masataka Yoshida in the eighth, appeared to be trying to bunt for a hit when all the team wanted was a sacrifice bunt.
Hamilton fouled off his first attempt, straight up missed on his second (on a pitch well outside the strike zone), and fouled off the third for strike three.
“We gotta get it down first,” Cora said. “Get it down and advance the runner. That’s the job there. If we get on base, that’s great, but the job is to get him to third base.”
Hamilton said he was “just trying to get it down.”
Lucas Giolito bent for most of his 4⅔ innings, then broke without recording another out.
He concluded his grind of an outing with four consecutive two-out walks in the fifth inning. The last two, to bottom-half hitters Ryan O’Hearn and Laureano, came with the bases loaded, forcing in the tying and go-ahead runs. Giolito threw 32 pitches in the frame, just 12 strikes.
Matz entered and induced a flyout from Jake Cronenworth, stranding Giolito’s three base runners and salvaging Giolito’s final line: five hits, four runs, six walks.
Giolito’s free passes were double his previous season-high (and as many as he had in his past five starts combined).
“I know with the way baseball works, the ‘L’ doesn’t go next to my name. But it should. That was really bad,” Giolito said. “I felt a little uncomfortable all day, but we were battling and pitching OK. In the fifth inning, I lost feel for my mechanics and just couldn’t make the adjustment. It’s inexcusable. I truly believe that if I had just gotten out of that fifth inning, made the adjustment, we would’ve won that game.”
Throughout, Giolito worked around a lot of hard contact from the Padres and benefitted from several highlight-reel plays by his defenders. Among them: right fielder Wilyer Abreu’s sliding grab of Jackson Merrill’s smoked line drive in the third inning, and second baseman Rafaela’s diving stop of Laureano’s would-be single in the fourth.
“It was incredible,” Giolito said of Rafaela’s snag. “He is one of if not the best defender in the league. It doesn’t matter where you put him. Whether he’s playing center or second base, he’s making plays like that.”
San Diego had five hard-hit balls turn into outs in the first four innings.
The only batter actually able to drive a run in early was Bogaerts, who hit a home run in the second — the first hit of his life against the Red Sox — and an RBI single in the third.
In his return from the injured list, Padres righthander Michael King was not sharp, allowing two runs, four hits, and two walks across two-plus innings.
King — a Warwick, R.I., native who went to Boston College — exited after 57 pitches, four fewer than he threw in his only minor league rehabilitation start. He had missed the previous 11 weeks because of a shoulder injury.
Kickstarting Red Sox rallies in both the first and third: Bregman, who doubled into the left-field corner in both innings.
The Red Sox could have had more early but did not capitalize on a second-inning, bases-loaded, one-out situation, other than to push King’s pitch count (34 in that inning alone).
That chance ended when Anthony, who had been ahead in the count, 3-1, whiffed at a changeup below the strike zone.
“We had a chance early on to put them away,” Cora said. “We had a chance against King and we didn’t cash in. Then you’re going to go one-on-one [with relievers] with them.”
Tim Healey can be reached at timothy.healey@globe.com. Follow him @timbhealey.