"He just lost it," Giants manager Bruce Bochy said. "... It's uncommon for him, but it happened."
"This one's on me. Nobody else," said Vogelsong.
Meanwhile, Parra threw almost as well as Peyton Manning. The D-backs right fielder recorded two assists, apprehending Brandon Crawford at home in the third inning and foiling Brandon Belt's fifth-inning attempt to stretch a single into a double.
"There's not a better arm in baseball," Bochy said. "He's as accurate as any outfielder I've seen throw the ball. He showed it tonight and helped win the ballgame for them. That's how good he is."
Parra should have had a third assist when Pablo Sandoval scored a fourth-inning run on Hector Sanchez's sacrifice fly. Television replays indicated that Sandoval, on base via an RBI triple, neglected to touch home plate twice -- first when he tried to bowl over Arizona catcher Miguel Montero, then when he dove back toward the plate in apparent recognition that he had missed it.
That gave the Giants a 2-0 edge, which soon evaporated.
Vogelsong was in the middle of what appeared to be a typical performance for him. Scattered opponents reach base. Rallies mount. Then Vogelsong retires the hitter he absolutely must subdue to escape the inning.
Against Arizona, Vogelsong left the bases loaded in the second inning, ignored a two-out single in the third inning and survived a leadoff hit in the fourth.
When he forged ahead on the count against Adam Eaton, 0-2, with two outs and nobody on base in the fifth, the D-backs appeared finished for that inning.
Then Vogelsong's usual pattern suddenly went awry.
Eaton fouled off a pair of 0-2 pitches and worked the count to 2-2 before doubling. After Willie Bloomquist walked, Vogelsong's wild pitch set up Paul Goldschmidt's two-run double. That was the first of four consecutive hits, including Martin Prado's RBI double and Aaron Hill's run-scoring single, that drove Vogelsong from the game.
"I made some bad decisions on some pitch selections and then on top of that I didn't execute the ones I picked," said Vogelsong (3-5), who entered the game with a 2.93 ERA in his previous five starts.
Citing specifics, Vogelsong lamented walking Bloomquist before throwing a 1-1 changeup that Goldschmidt hit. That, Vogelsong said, was "probably not a pitch I wanted to throw there. It's one of those things that, when you're in the moment, it sounds good and it makes sense."
Before leaving the clubhouse, Vogelsong approached Sanchez, his catcher, patted him on the back and began a brief chat. Though the conversation remained private, it was easy to surmise that Vogelsong apologized for shaking off Sanchez.
"I didn't get the job done tonight," Vogelsong said. "That's the bottom line."
The outcome knocked the Giants (62-78) back into last place in the National League West, a half-game behind idle San Diego (62-77). San Francisco is trying to avoid becoming the second team to finish last one year after winning the World Series.