The loss sliced the Dodgers' NL West lead to 2 1/2 games over the surging Colorado Rockies, but Torre said he was happy to take two of three from the Diamondbacks.
"I'm very positive about this series," Torre said. "This was a disappointment, this game. You'd like to win the ballgame, but you had your opportunities."
Last season, the Diamondbacks and Dodgers dueled into September before Los Angeles pulled away. This year, the Diamondbacks have been out of contention for months, but they relished playing the spoiler role in the division race, if only for one night.
"I think the whole NL West might have been watching that game," said Arizona manager A.J. Hinch, whose team ended a six-game skid.
"I left my shoulder a little down," Troncoso said.
As it turned out, that was the only ball that left the infield in the bottom of the ninth.
Trent Oeltjen ran for Parra and took third on Ryan Roberts' sacrifice. After intentional walks to Stephen Drew and Justin Upton, Troncoso missed with a 3-2 fastball to Mark Reynolds, who had fouled off a pair of pitches with two strikes.
"I was just trying to put the ball in play," Reynolds said. "I just fouled off some tough pitches and was able to work a good AB."
Torre said he walked Drew and Upton to set up a force at home. He also hoped Troncoso could strike out Reynolds, who leads the majors with 190 strikeouts.
Had that happened, the Dodgers still would have had to retire Miguel Montero, who homered, doubled and singled.
"When you're going through the middle of the lineup, you really don't have a lot of choices," Torre said. "Upton certainly has been doing a hell of a job, and Reynolds, the one thing you feel you have going is he swings and misses a lot."
Los Angeles led 3-2 before Upton tied it with a run-scoring grounder to third in the fifth.
"Unfortunately, we couldn't cash in," Torre said.
Los Angeles' Jon Garland started against his former team for the second time in six days. Arizona dealt Garland to the Dodgers during a series in Los Angeles on Aug. 31.
Los Angeles gave Garland a quick 1-0 lead in the first, when Rafael Furcal led off with a triple and scored two outs later on Ramirez's bad-hop single off third baseman Reynolds' glove.
The Diamondbacks tied it in the second on Montero's 14th homer. Five pitches later, Chris Young also hit a drive to right for his fifth homer in four games and Arizona's seventh set of back-to-back shots this season.
Los Angeles rallied in the fourth with consecutive homers of its own, by Ramirez and Loney -- the eighth time the Dodgers have done it this year.
Garland went six innings, allowing three runs and six hits.
Dodgers LHP Randy Wolf will miss his scheduled Friday start at San Francisco with elbow irritation. Hiroki Kuroda will take Wolf's turn. ... LHP Scott Schoeneweis threw to hitters before batting practice, and he's likely to return to the Diamondbacks' bullpen in the next week. Schoeneweis was on the disabled list from Aug. 11-Sept. 7 because of depression following his wife's death.