With the D-Backs up, 4-1, and one out in the fourth, the Giants had runners at first and second with Alou at the plate. Vargas knew he needed a groundball in the worst way in the hopes that Arizona could turn a double play and get out of the inning with its lead intact.
Vargas got the grounder he wanted, but it bounced off Tracy and into shallow left. One run scored on the play and Vargas was able to get Mark Sweeney to fly out for the inning's second out.
Vargas then jumped ahead of Pedro Feliz 1-2 and was one pitch away from making Tracy's error essentially irrelevant. The right-hander tried to get an outside fastball past Feliz and instead watched him hammer it to right-center to score two and tie the game at 4.
"We didn't play the best defense for [Vargas] later but we certainly made some good plays for him early and sometimes it's the pitchers job to pick up the position players, too," D-Backs manager Bob Melvin said.
"That's part of the game," Vargas said of the error. "Everybody goes out there and tries to do their job."
The play signaled a change in both the Giants and Tracy's fortunes on the evening.
Tracy, who had six errors all year coming into the game, it was the first of three on the evening, while the three unearned runs were the first of 10 unanswered runs for San Francisco.
"We were ahead and then we let them back in it a little bit and they just kept going and putting more and more pressure on us and scored more and more runs," Melvin said. "We didn't have an answer for it."
It looked like they had the beginnings of one in the seventh. Down 7-4 at the time, Craig Counsell singled to start the frame and after an Eric Byrnes flyout, Tracy stepped to the plate having already doubled twice.
This time it was a double play rather than a double and after Conor Jackson hit into one the following inning it was clear that this game was going to belong to the Giants.
"Those are momentum shifters right there," Melvin said. "We've been pretty good about battling, battling, getting guys on and getting some key hits and then now two double play balls like that really can deflate you a little bit. Those are probably at the time for us to try to turn the tables on them."
The Giants made sure that the D-Backs didn't have another comeback in them when they tacked on four runs, three of which came on Barry Bonds' 717th career homer, off Jose Valverde.
It was another night of struggles for Valverde, who has allowed a stunning 17 runs in his last 9 1/3 innings. The right-hander had converted 12 straight save appearances at one point, but has fallen off since and lost the closer's job to Jorge Julio.
"We'll continue to work with him," Melvin said. "Sometimes as a closer you're used to coming in in that closing condition and that's where your adrenaline gets going and that's what you're used to, but no excuses. He's going to have to pitch better. The numbers over the last nine or ten innings aren't very good."