SAN FRANCISCO Matt Cain knew what he was signing up for.
The veteran right-hander has received the worst run support in the majors since 2006, keeping him from being a winning pitcher even as his ERA has hovered below 3.50.
Inexplicably, that support has dwindled even further since Cain signed an extension last month that will keep him in orange and black for the better part of the next decade.
Cain threw eight strong innings in a 2-1 loss to the Miami Marlins at AT&T Park on Tuesday, but the Giants could muster only a Pablo Sandoval solo homer off Marlins right-hander Ricky Nolasco.
The Giants had a chance to make a winner of Cain in the eighth, but Buster Posey hit into an inning-ending double play with the bases loaded.
"That's a situation more times than not you're going to get runs," Cain said.
This marked Posey's first time facing the Marlins since the catcher's season ended with left leg and ankle injuries in a collision at the plate May 25, 2011, with the Marlins' Scott Cousins, who is trying to make his own comeback from injury at Triple-A New Orleans.
Cain was perfect the first time through the order, throwing just 28 pitches. But the Marlins struck in the fourth when Jose Reyes walked, stole second, took third on a wild pitch and strolled home on Hanley Ramirez's single through a drawn-in infield.
The Marlins scored in a much more efficient manner in the fifth inning when Giancarlo Stanton lined a home run just inside the left-field foul pole.
The Giants left six runners on base, continuing a season-long trend and were 1 for 9 with runners in scoring position. Following Tuesday's loss, they are averaging 3.9 runs per game.
Ryan Theriot's sharp grounder with two outs in the bottom of the ninth bounced over the bag at first but was ruled foul, and manager Bruce Bochy came out to argue. Theriot then grounded out to end the game.
"It sure is a tough one for Matt. He gives up two runs in eight innings. He did his job," Bochy said. "Watching Theriot's reaction, he thought it was fair. That was a bad break. Still, we had our chances and didn't come through."
Notes The Giants placed left-handed reliever Jeremy Affeldt on the 15-day disabled list because of a right knee sprain he suffered at home while interacting with his 4-year-old son.
Travis Blackley was called up from Triple-A Fresno to take Affeldt's spot as the second left-hander in the bullpen.
The injury is expected to heal in seven to 10 days.
Aubrey Huff (anxiety disorder) took early batting practice and spoke with Bochy but declined interview requests. Bochy said Huff might be activated when eligible to come off the disabled list Monday.
Left-handed reliever Dan Runzler (upper back strain) visited the clubhouse to see team doctors. Bochy said Runzler "felt a little something" while pitching in an extended spring training game in Scottsdale, Ariz., but the Giants were confident that it was just an issue with scar tissue.
Second baseman Freddy Sanchez (right shoulder) threw for the first time since his rehab was temporarily shut down last week.
Angel Pagan extended his hitting streak to a career-high 15 games with a third-inning single.