DENVER -- The Giants reached the season's halfway mark Sunday with a performance that almost cruelly demonstrated what they must accomplish during the rest of the year to avoid irrelevance.

They again lacked the critical hit that would further their chances for a victory or even clinch one. This shortcoming forced them to endure a game that was as excruciating as the previous evening's was exhilarating: A 15-inning, 4-3 loss to the Colorado Rockies that ended with Todd Helton's bases-loaded sacrifice fly.

San Francisco's eighth defeat in nine games sealed its fifth consecutive series loss. The fourth-place Giants dropped three out of four games to the Rockies during this holiday weekend and fell a season-high 7 1/2 games behind National League West-leading San Diego.

Since June 22, when the Giants defeated Houston to climb nine games above .500 (39-30) and match a season high, they've been outscored 67-42 while losing 10 of 12 games. Whatever opportunistic hitting they sustained earlier in the season has dissolved; the dominant pitching that seemed to be a given has unraveled. Instead of striving to catch San Diego, San Francisco (41-40) is struggling to stay above .500. Ominously, half of the Giants' defeats have been dealt by division opponents, against whom San Francisco is 9-20.

So manager Bruce Bochy had more than one wish when asked what the Giants must do to improve their fortunes.

"We need to be more consistent on both sides of the ball," Bochy said, sounding vaguely like a football coach. He came down squarely on the offensive side by adding, "Really, it's going to come down to getting some timely hits. That's what has been missing more than anything."

The Giants went 1-for-9 with runners in scoring position Sunday, which might have occupied Bochy's thoughts when he made this remark. They squandered their most promising extra-inning opportunity in the 13th, when Aubrey Huff opened the inning by tripling off right fielder Seth Smith's glove. Rockies reliever Esmil Rogers responded by striking out pinch-hitter Pat Burrell and Eli Whiteside. After intentionally walking Juan Uribe, Rogers finished his escape by coaxing a fielder's-choice grounder from Edgar Renteria, who went 0-for-6.

To their credit, the Giants endured no hangover after Saturday's stirring 11-8 triumph. If anything, they delivered another determined effort. Not only did they erase a 3-0 deficit by pulling even in the eighth inning, which featured a historic tandem of home runs by Nate Schierholtz and Andres Torres, but they also played tough enough to contribute to the longest game in Coors Field history -- five hours, 24 minutes. It also was the Giants' longest game in terms of innings since they lost, 4-3, at San Diego in 15 innings on June 19, 2001.

The Giants' effort compelled Bochy to reassure them after they trudged into the clubhouse.

"I told them that's a tremendous job on their part," he related.

The Rockies might have felt differently after stranding a franchise-record 20 runners, including 12 in scoring position. They left the bases loaded in the 10th and 13th innings and had a runner thrown out at home plate to end the 14th.

Then came the 15th. Dexter Fowler, who went 10-for-16 (.625) in this series with seven walks, three RBIs, three triples and seven runs scored, opened the Rockies' half of the inning by tripling to left-center field off Guillermo Mota (0-3). As they did in the 14th, when Smith reached third with nobody out, San Francisco intentionally walked the next two batters to set up a force at home -- the Giants' only alternative. Helton ended matters by lifting the first pitch to medium-deep left field, where Torres caught the ball but had no play on Fowler.

The Giants' eighth-inning rally included echoes of Saturday night's victory and of their glorious past.

Rockies starter Jason Hammel permitted only two runners to reach scoring position while blanking the Giants for seven innings. Then Schierholtz, whose seventh-inning triple Saturday launched San Francisco's comeback from an 8-7 deficit, pinch-hit and christened the Giants' big eighth with his second home run of the season.

Torres followed with an inside-the-park homer -- a sharp grounder past first base that proceeded into the right-field corner and caromed away from Ryan Spilborghs. The speedy Torres, who was nearing third base by the time Spilborghs grabbed the ball, slid home under second baseman Jonathan Herrera's high throw. Later, Travis Ishikawa, whose grand slam Saturday highlighted the Giants' seven-run outburst against ultra-ace Ubaldo Jimenez, concluded the scoring with an RBI single.

"To be honest with you, I was going to second and [third-base coach Tim Flannery] told me to keep going," Torres said.

Hammel disparaged the Giants' homers.

"The eighth inning was kind of laughable for me -- a one-handed, one-armed swing that leaves the yard and a 29-hopper that comes around for another run," he said. "If that doesn't happen, that game's over three hours ago."

The Giants' rally averted another hard-luck defeat for Matt Cain, who yielded three runs and six hits in seven innings. It also unearthed an intriguing fact.

According to the Elias Sports Bureau, the last time an inside-the-park homer was part of a back-to-back home run combination for the Giants was June 1, 1966, at Atlanta. Willie Mays accounted for the inside job before Willie McCovey cleared the wall. Final score: Giants 4, Braves 3.

The Giants mirrored history, but couldn't fully duplicate it.