With a 4-2 loss to the San Diego Padres on Wednesday, they guaranteed themselves a sub-.500 record when the league's best players travel to AT&T Park for the July 10 midsummer classic.
Their first half has been a tremendous disappointment for Giants ownership, which hoped to boast of a first-place standing while chatting up guests at the mixers, galas and cocktail parties.
But if anyone has a glass full of bitters, it's Matt Cain.
The 22-year-old right-hander bordered on dominance again, lowered his ERA and yet took another inexplicable loss. Jose Cruz Jr. hit a tiebreaking single off Cain in the eighth inning and shortstop Kevin Frandsen botched a grounder that allowed two more runs to score as San Diego took two of three in the series.
Cain is 2-9 despite a 3.38 ERA, the lowest among Giants starters. Even more remarkable, the Giants are 2-14 in his starts.
"He's got some of the best stuff in the game," Giants center fielder Dave Roberts said. "It's so unfortunate for such a great kid and competitor to have this kind of bad luck. It hurts all of us."
It's been a system-wide failure. If the Giants could have managed an 8-8 record in Cain's outings -- certainly reasonable, since he has pitched 11 quality starts out of 16 -- they would be 39-38 and within striking distance in the National League West.
Instead, they are 33-44, buried in the standings and pondering a fire sale.
Cain slammed his glove in the dugout after manager Bruce Bochy removed him in the eighth inning. Cain hasn't won in eight starts since May 13 and has taken the loss in each of his past four outings despite a 2.93 ERA.
But his rare burst of frustration wasn't directed at the lack of support. He was upset that he didn't pitch around Cruz after falling behind in the count.
"I messed up," Cain said. "I laid one in there, pretty much. I had the opportunity (with a base open) to go on to the next guy. He took advantage of what I did wrong."
Cain couldn't sneer at his hitters. He stepped in the box himself and examined Greg Maddux's assortment of cutters, sinkers and other pitches that looked like they were coming out of a funhouse mirror.
"The ball moves a foot and a half," Cain said. "It's not fair, really."
Maddux allowed only a solo homer to Pedro Feliz in the second inning on the way to his 340th career victory. Since coming to the National League West with the Dodgers in a trade last July, Maddux is 3-0 with a 0.96 ERA in four starts against the Giants.
No wonder the Giants went after him so hard as a free agent prior to the 2004 season.
The Giants hit a few pitches on the screws, notably Bengie Molina's line out that stranded two in the first inning. Molina also flied out to the warning track twice.
"I think the key was not getting killed early," Maddux deadpanned.
Khalil Greene's home run tied it in the fifth and Marcus Giles hit a two-out double in the eighth that landed in front of Roberts' diving attempt. Cruz followed with the game-winner, sending Cain to another loss.
Trevor Hoffman stayed perfect in four save opportunities against the Giants and Bochy, his former manager. Hoffman retired Mark Sweeney to end the game and strand would-be pinch hitter Barry Bonds in the on-deck circle.
Cain has spoken with teammates and family about handling his rotten luck, and he seems to be finding positives.
"I've had to pitch in tight ballgames and I know I can use that to my advantage," Cain said. "I can use that the rest of my career."
Contact Andrew Baggarly at email@example.com.