SAN FRANCISCO -- Even the Giants' best news of the day was negative. Starter Matt Cain watched from AT&T Park's radiology clinic as his bullpen imploded in a seven-run fifth inning that saw 11 Pirates come to the plate, leading to a 10-5 Pittsburgh victory in Thursday's series opener.
The silver lining for San Francisco is that Cain, who was forced to exit in the fourth inning when he was struck by a Gaby Sanchez line drive, received negative X-rays and suffered nothing more than a contusion to his throwing arm.
The Giants fell to 32-34 (.485) at AT&T Park this year, their fourth-worst home winning percentage since Pac Bell Park opened in 2000. San Francisco has been outscored 31-9 through the first four games of its current homestand.
The Giants need to win at least seven of their final 35 games to avoid their first 100-loss season since 1985 -- the only such season in franchise history.
Starting pitcher report
A day after manager Bruce Bochy acknowledged his team "drifted mentally" in a 12-1 loss to the Red Sox, Matt Cain was less than locked in from the start. His early lack of command put the Giants in a hole.
Cain, who was 3-0 with a 1.24 ERA in his last six starts against the Pirates, started the game ceding consecutive singles to Jose Tabata, Neil Walker and Andrew McCutchen -- all on fastballs left elevated and over the heart of the plate. The 21st pitch of the inning mercifully resulted in a double play.
The second inning wasn't better, as a pair of mistakes were hammered by Garrett Jones and Jordy Mercer for solo home runs, a 3-0 Pirates lead and a mound visit from pitching coach David Righetti. Cain has now allowed 21 home runs on the season, one away from his career high with at least five scheduled starts remaining.
Then came the fateful fourth, when Gaby Sanchez's leadoff line drive thumped off Cain's pitching arm and ended his night prematurely.
Cain's final line: 3 1/3 IP, 7 H, 3 ER, 3 K, 64 P, 2 HR, ND.
Guillermo Moscoso had as much time to warm up as he needed when he entered for the injured Matt Cain in the fourth. He used his time wisely, and promptly struck out Jordy Mercer and Jeff Locke to end the inning.
Moscoso stayed in to drop down a sacrifice bunt in the bottom of the frame, but his success ended there. He teed up the Pirates' monster fifth inning by loaded the bases on a hit batsman and two walks before yielding to Jose Mijares.
Mijares' second offering was hammered by Pedro Alvarez for a ground-rule double. And the lefty allowed another double, two singles, a walk and two sacrifice flies before he got Neil Walker -- the 11th batter of the inning -- to ground out and stop the bleeding with the Giants trailing 10-3.
Moscoso completed two-thirds of an inning and was responsible for three earned runs, taking the loss to fall to 1-2 on the season. Like Mike Kickham the night before, the nightmare inning was all Mijares, as the bullpen stayed quiet.
Jean Machi pitched a perfect seventh inning and a scoreless eighth. Javier Lopez handled the ninth.
At the plate
The Giants showed resilience in coming back from an early 3-0 deficit, and had AT&T Park raging like 2012 when Marco Scutaro delivered a game-tying, two-run single with two outs in the fourth. But there was little life after the Pirates responded with seven runs in the top of the fifth.
Brandon Crawford gave the team a spark in the eighth inning, though, when his pinch ground rule double scored two. It was the Giants' second hit of the night with runners in scoring position after going 1-for-26 (.038) in such situations against the Red Sox. For comparison, the first-place Pirates were 4-for-9 (.444) with runners in scoring position Thursday.
Buster Posey entered the game 1-for-his-last-15 with runners in scoring position. He failed to record a hit when he came to the plate with runners at the corners and one away in the third inning, but his sacrifice fly to the left-field corner -- which elicited an audible AT&T Park groan when it was caught on the warning track -- was plenty deep to score Marco Scutaro from third and get the Giants on the board.
Pablo Sandoval, who missed the previous two games with a sore back, followed a leadoff walk in the second inning with a double play-ball on the first pitch he saw. He grounded out on the first pitch he saw in the sixth inning, too, but mixed in a rally-starting walk to lead off the fourth.
Left fielder Brett Pill put together a solid game at the plate, recording three hits, including a double in the eighth-inning rally.
Bochy would have thrown his challenge flag in the fourth inning when Jeff Locke's pitch to Joaquin Arias skipped off shortstop's toes. Arias reacted as such, but home plate umpire Vic Carapazza decided it was a ruse and kept Arias at the plate. Even after Bochy argued the call and Carapazza called a meeting of the minds, the umpires incorrectly prolonged Arias' at-bat, which resulted in an inning-ending lineout to first.
In the field
The Giants were sound with the gloves behind Cain, who made the defensive play of the game for the Giants.
With runners at second and third and one out, Cain's inside fastball broke Russell Martin's bat and induced a weak comebacker. Andrew McCutchen broke from third, but Cain bounced off the mound to field the ball and flipped it to Buster Posey with plenty of time to apply the tag.
Scutaro also made an impressive play charging a weak grounder, converting the unique 1-4-3 putout with a nifty flip to first on the comebacker that chased Cain from the game.
Sandoval nearly converted a Golden Great when he dove toward the line to snare Russell Martin's ground ball. But his throw to first base short-hopped Brandon Belt and the generally sure-handed first baseman couldn't dig it cleanly. On the next batter, Sandoval started the 5-6-3 double play to clear the bases.
Bochy raised the white flag in the later innings, lifting Scutaro and Posey in favor of Nick Noonan and Hector Sanchez.
The Giants announced a paid attendance of 41,733, keeping the 230-game sellout streak intact. But it was a sparsely-populated lower deck that watched the game's final out.
The Giants and Pirates take the field for Game 2 of their four-game series Friday night at AT&T Park. Giants left-handed pitcher Madison Bumgarner (11-7, 2.82) will oppose Pirates right-hander Charlie Morton (4-3, 3.67).