In a tie game in the eighth inning against the Orioles, he was brought in to face Orioles slugger Chris Davis. Hynes left a slider out over the plate to Davis, who hit a towering three-run homer to lead Baltimore to a 10-3 victory at Petco Park.
It was Davis' Major League-leading 41st home run and traveled an estimated 453 feet, tying it for the second-longest homer in Petco Park history, along with Russell Branyan (2006) and Andruw Jones ('06). Adrian Gonzalez launched a ball 458 feet in '09.
"Usually a swing like that and contact like that, usually indicates it's not that great of a pitch," said Padres manager Bud Black.
The game was tied 3-3 through seven innings before the Padres bullpen allowed seven runs over the final two frames.
Luke Gregerson (5-6) allowed a pair of singles to start the eighth inning before being removed so Hynes could face Davis.
"It was loud, but he's not picking on anybody," said Orioles manager Buck Showalter. "The thing about Chris is he's so lethal -- he may have some bad at-bats, but you never think he's not a swing away from really doing something good for you."
Hynes also allowed a double to the next hitter, Matt Wieters, who would score on a sacrifice fly later in the inning. Hynes and Gregerson each faced two batters, allowed two hits and were charged with two runs apiece.
The game was put out of reach in the ninth when the Orioles added three more runs off reliever Sean O'Sullivan, highlighted by a two-run single by J.J. Hardy to push the score to 10-3.
Francisco Rodriguez (2-1) pitched a scoreless seventh in relief for his first victory with the Orioles (63-51), who won both games of this two-game series in San Diego, after the Padres won both games in Baltimore in May.
Padres starter Eric Stults, who was 0-3 in three starts since the All-Star break, pitched much better in this game. He went seven innings, in which he allowed three runs (two earned) and struck out six. Padres starters have allowed three earned runs or fewer in 10 straight starts dating back to July 27 at Arizona.
"It was a battle. My location wasn't great, but I was able to keep us in the game," Stults said. "Today, I felt like I had some mental errors. Mentally, I wasn't as sharp."
The Orioles got to Stults in the second inning with a home run by Hardy to give them a 1-0 lead.
Baltimore scored an unearned run in the fourth by taking advantage of some sloppy Padres defense. San Diego tied a season high with three errors.
Manny Machado started the inning by reaching on an error after an errant throw from second baseman Jedd Gyorko. The next batter, Adam Jones, singled to center field, but a wild throw from center fielder Alexi Amarista trying to get Machado at third landed in the Orioles' dugout and allowed a run to score.
Machado added to the Orioles' lead with an RBI single in the fifth inning to make it 3-0.
The Padres squandered early scoring chances again, after going 1-for-12 with runners in scoring position on Tuesday. They had a runner in scoring position in the first and second inning, but couldn't score and then allowed Orioles starter Miguel Gonzalez to settle into a groove.
After a leadoff double in the second inning, Gonzalez proceed to retire 12 of the next 13 batters batters and seemed to be in complete control through the fifth inning.
Then Gyorko tied the game in the sixth inning when he deposited a 2-0 fastball over the center-field wall for a three-run homer, his 10th of the season.
Gyorko is 7-for-65 since coming off the disabled list on July 12, and two of those hits have left the yard.
"It felt good to stay down on a fastball and drive it and actually hit it with some force," said Gyorko. "I feel like I'm starting to swing at strikes and I'm laying off balls out of the strike zone."
For a moment, Gyorko's blast gave the 21,206 fans at Petco Park a glimmer of hope that the Padres (52-62) may cap a comeback before a six-game road trip begins on Friday.
Then Davis took the air of the building with his towering blast.
"That's what the home run does, gets you right back in the game," Black said. "And then, conversely, a big home run took us out of the game."