Dodgers manager Don Mattingly stepped onto the field and told the umpires that Posey was actually listed fourth in the Giants' lineup and that Pablo Sandoval should have hit third.
Because of the Giants' mistake, Gregor Blanco -- who had scored on Posey's double -- returned to the bases, Sandoval was charged with a groundout to Dodgers catcher Tim Federowicz and Posey returned to the plate, where he flied out to right to end the inning.
After the umpires sorted out the issue and the inning concluded, the score remained 0-0, and the Giants missed out on scoring in the first inning for the second consecutive day after not doing so since June 18.
The last Dodgers opponent caught batting out of order was the Cincinnati Reds on May 21, 1994.
After the game, Giants manager Bochy took responsibility for the miscue, but added that there was a "perfect storm" of factors leading to batting out of order, including Bochy's All-Star Game responsibilities leading up to Saturday's game as well as a new electronic board the Giants began using in the clubhouse Friday. Bochy said it was transferred incorrectly onto the iPad that displays the lineup in several places, including the clubhouse.
"You feel horrible," Bochy said. "It cost Buster a double and an RBI. There's not a worse feeling. ... [Winning] does soften the blow."
Bochy admitted that he was confused in the middle of the at-bat as to why Posey was at the plate.
FOX had a microphone on home-plate umpire Tony Randazzo for the broadcast, and Posey could be heard telling him, "I'm third everywhere, the clubhouse, scoreboard."
"I looked at the lineup in [the clubhouse]," Posey said after the game. "I looked at the scoreboard and I was batting third.
"We're such creatures of habit and that was a first for me at any point in baseball."
Posey was also listed third on the lineup given to the media prior to the start of the game, but there was some pregame confusion during Bochy's media session.
After Posey had primarily batted fourth most of the season, Bochy moved his catcher to third in the lineup June 7, where he has appeared most of the time since.
Posey hit cleanup in Friday night's loss, but Bochy was asked about his place in the order after the pregame lineup had him listed as returning to the No. 3 slot.
"He was in there for a while, but we were doing pretty good with him in the four-hole. He had a lot of success, but I don't think it matters what hole you put him in," said Bochy before the game, adding that the team's slide has coincidentally come with Posey in the third spot. "You can call it being superstitious or whatever, but I'm going back to where we did have had success, and that's Pablo in the three-hole, Buster in the four-hole."
When Posey batted ahead of Sandoval, the Giants violated Major League Baseball's Rule 6.07, which states, "A batter shall be called out, on appeal, when he fails to bat in his proper turn, and another batter completes a time at bat in his place." Additionally, "when an improper batter becomes a runner or is put out, and the defensive team appeals to the umpire before the first pitch to the next batter of either team, or before any play or attempted play, the umpire shall (1) declare the proper batter out; and (2) nullify any advance or score made because of a ball batted by the improper batter or because of the improper batter's advance to first base on a hit, an error, a base on balls, a hit batter or otherwise."
Had the Giants realized the error before Posey's at-bat ended, Sandoval could have replaced him and assumed the batting count Posey faced at that point.
"[Bench coach] Trey Hillman saw it as soon as he stepped in the box," Dodgers manager Don Mattingly said. "It can happen easily when you make up the lineup with those computers."
It wasn't the first time Bochy and Mattingly have been involved in some rules confusion the past few years. In 2010, with Mattingly filling in for Joe Torre as Los Angeles manager, Mattingly was charged with two mound visits on the same trip. Closer Jonathan Broxton was forced to leave the game after not throwing a pitch when Mattingly stopped on his way back to the dugout and returned to the mound to arrange the defense and Bochy pointed out the violation to the umpiring crew.
"No, I didn't think about that," Bochy said. "They have their lineup card right in front of them."