SAN FRANCISCO -- Yu Darvish and the Padres were on the verge of escaping a nobody-out, bases-loaded jam with just a one-run deficit in the fifth inning of Wednesday's 4-2 loss at Oracle Park.

Instead, an overturned out call at the plate changed the tone of the game.

With two outs and two on, Joc Pederson smacked a single to right field to extend the Giants' rally. Fernando Tatis Jr. added to a growing list of reasons not to test his arm by unleashing a 99 mph dime to backstop Gary Sánchez, who tagged San Francisco's Blake Sabol several steps in front of the plate.

Sabol was initially ruled out, but the Giants successfully challenged the call on a blocking violation, adding another run to their tally.

"That was another dagger to us," Tatis said.

The official explanation was that Sánchez began the play in an illegal position, meaning he was not fully in front of the plate in fair territory.

Catchers are allowed to move out of a legal position in reaction to an incoming throw, an exception that is granted at the discretion of officials. Sánchez said he positioned himself in the way that set him up best to make the play.

"Maybe I could have stayed in front of home plate or something," Sánchez said in Spanish through team broadcaster Pedro Gutiérrez. "But in that position, I'm just looking at the ball trying to figure out where it's coming and trying to make sure I get it. The ball took me, again, toward the third-base side, and that's eventually what happened."

Home-plate umpire Quinn Wolcott told a pool reporter that umpires are told not to look for blocking calls on the field.

“I don’t worry about starting position -- it’s hard enough to officiate that play," Wolcott said. "I need to read the throw to get in position to see a tag. … So I just try to officiate out/safe at the plate.”

Padres manager Bob Melvin, who was ejected after arguing the call, said the rule fails to account for the position of the runner.

"The baserunner's way down the line toward their dugout. At some point in time, you have to go get him," Melvin said. "The throw took [Sánchez] up the line as well. Based on where he started, it looked like they showed the replay from when the throw was already on the way, and as a catcher, you have to have some feel for that. You've got to also understand the impact and where the runner was. To me, it was just one of the worst calls I've seen this year."

When play resumed in the fifth, things began to spiral for Darvish. He proceeded to allow back-to-back RBI singles before getting the final out, and all of a sudden, the Padres trailed 4-0.

"You never know where the game's going to go," Melvin said. "But at that point in time, it's 1-0, Yu's out of the inning and there aren't three more runs on the board."

Darvish pushed back on the idea that the overturned call had an impact on his performance, taking responsibility for the way the inning proceeded afterward.

"My take is that it didn't affect me," he said in Japanese through interpreter Shingo Horie. "It didn't affect my pitches, it didn't affect how I pitched. They just got to some of the balls. From my end, I was just pitching as I was before."

The Padres had won three straight series before dropping their four-game set with the Giants, who surged to their 10th consecutive win. Outside of the fifth inning, the problems that sunk San Diego in the first two games of the series persisted on Wednesday.

The Padres struggled to string anything together against a Giants bullpen that has been nothing short of dominant over the past month. San Diego's leadoff batter reached and was subsequently stranded in each of the first six innings Wednesday as the team hit into four double plays and went 1-for-12 with runners in scoring position.

"We're not even thinking about runners in scoring position. We're not thinking about any of that. We're going out there and playing baseball," said Manny Machado, who ran into an out on the bases in the fourth inning. "Darvish gets into a little bit of a pickle there, and then to get away with it with just one run, it's a hell of an inning for us. … It's a different ballgame if it's 1-0, not 4-0."