Giants lament missed chances vs. Astros

HOUSTON -- This was the kind of game the Giants typically win.

It was decided by one run, the margin by which they had captured nine of 12 such decisions entering the contest. The Giants opened the scoring; they previously were 14-5 when that happens.

San Francisco's final pitcher was Jeremy Affeldt, who rarely yields home runs. George Springer belted a homer off him to break an eighth-inning tie. The Giants' final hitter was Buster Posey, who had driven in all three of their runs and came to bat with runners on the corners. He tapped a first-pitch comebacker to reliever Luke Gregerson, sealing the Giants' 4-3 loss Wednesday to the Houston Astros.

The Giants split the two-game series against the American League West leaders. But manager Bruce Bochy left Minute Maid Park believing his club could have completed a mini-sweep. Too many mistakes, he said, weighed them down.

"Our execution got us tonight," said Bochy, citing the Giants' runners left on base (10), their hitting with runners in scoring position (2-for-8), and the double plays into which they grounded (two).

Bochy observed the Giants "should have had two or three more runs earlier" in the game. But though they hit safely in each of the first six innings, five of the nine hits they accumulated in that span came with two outs. The Giants had no margin for error, though Posey delivered a two-out RBI single in the first inning and added a two-run homer in the fifth, which put the Giants ahead, 3-1.

Video: SF@HOU: Posey launches a two-run homer to left

After Houston pulled even against Tim Hudson on homers by Jason Castro in the fifth and Luis Valbuena in the sixth, the Giants tried baserunning ploys to maximize their offense.

With Brandon Belt on first base and one out in the eighth, Bochy called for a hit-and-run with Casey McGehee batting. Bochy was mindful of McGehee's penchant for grounding into double plays. The third baseman began the game with 11, tied for the Major League lead. But Belt was thrown out after McGehee flailed at a 2-1 pitch.

"Those little things -- productive outs, the missed hit-and-run -- catch up with you in a close ballgame," Bochy said.

Video: SF@HOU: Belt is out on steal, Giants challenge in 8th

The Giants began the ninth trailing after Springer became the first right-handed batter to homer off Affeldt since San Diego's Jesus Guzman on June 18, 2013. Brandon Crawford doubled to christen the ninth, but tried to advance to third base on Nori Aoki's grounder to shortstop Jonathan Villar and was thrown out.

"To me, I don't think [that] was a bad play," Posey said, defending Crawford. "He was being aggressive. The ball was hit behind him. That's what you're taught. When the ball's either at you or behind you, go to third."

The Giants still managed to put the potential tying and go-ahead runs on base for Posey, who was 3-for-9 with a home run lifetime off Gregerson. But the crafty right-hander flung an 80 mph slider that rendered Posey powerless.

"That's his pitch," Posey said. "You hope you either swing and miss or it goes foul."