SAN FRANCISCO – For a moment, the Giants looked poised to hand the St. Louis Cardinals a taste of what had gotten them here. The Cardinals, who played their way into the National League Championship Series by overcoming a six-run deficit, mounted that same lead in the fourth inning of Game 1 before watching the Giants carve a chunk out of it minutes later.

On this night, though, the initial hole proved too deep. The Giants fell to the Cardinals 6-4, and the big difference between these playoffs and those of 2010 in San Francisco appeared again in the form of left-hander Madison Bumgarner walking slowly off the mound in the fourth inning, having surrendered all six runs.

The Giants have not received a quality start from their rotation in these playoffs and have yet to win a game in front of the orange-towel-waving enthusiasts at AT&T Park. As in the first round, the Giants will have to play their series against the Cardinals from behind, with Game 2 this evening before the series shifts to St. Louis.

"We just have to turn the page," said center fielder Angel Pagan. "It's a long series, and we've just got to keep the good attitude we have right now. It happened in the last series. But we're not going to go by that. We're going to come back (tonight) and play hard."

Bumgarner, suddenly appearing quite vulnerable, has pitched eight innings total in his two playoff starts and allowed 10 runs. Both outings came at home, where the left-hander had a 2.33 ERA during the regular season.

On Sunday, David Freese lined Bumgarner's full-count slider into the left-field seats to give the Cardinals a 2-0 lead in the second inning. Two innings later, Carlos Beltran hit a pitch that was meant to run inside for his 14th career postseason home run, a two-run job that capped a four-run inning for the Cardinals and ended Bumgarner's night.

Catcher Buster Posey said Bumgarner just "struggled with command." Manager Bruce Bochy said it looked like the pitches that led to the Cardinals' two biggest blows of the game simply missed their mark.

"That's the way it's been the past few starts, not a whole lot of life on the ball," Bumgarner said. "At the same time, you've got to find a way to make pitches in cases where the stuff might not be as sharp. You've got to find a way to get it where it's supposed to go."

Bumgarner, who struggled down the stretch for the Giants, said at the time that he was going through some mechanical issues. That isn't the problem right now, he said.

"It's been a few starts where stuff just hasn't been there like it usually is," Bumgarner said. "It's not anything mechanical. Mechanics are fine."

The Giants nearly bailed him out in the bottom of the fourth, scoring four times with two outs to knock Cardinals starter Lance Lynn out of the game. Brandon Belt drove in one with a single, Gregor Blanco laced a triple into right-center to score two, and Brandon Crawford's one-hopper off the right-field wall plated Blanco.

Pagan then came up with runners on first and second and two outs and hit a chopper that looked bound for center field. But Cardinals second baseman Daniel Descalso made a diving play and a desperate flip to second to end the inning. Pagan thought he had a hit.

"But he made a great play," Pagan said. "You've got to give him credit."

The Giants threatened again in the fifth with two on and two out, but in an early move to protect a 6-4 lead, Cardinals manager Mike Matheny summoned his only left-handed reliever, Marc Rzepczynski, to face Belt.

Belt flied out to left-center.

In fact, five Giants relievers combined to hold the Cardinals hitless after Bumgarner left the game.

But the St. Louis bullpen was just as stingy, not allowing another hit after the fifth inning until Pagan singled off closer Jason Motte with two outs in the ninth.

"Makes it easier when you do get a quality start, but when it doesn't happen, you try to get through the game and keep it close," Bochy said. "We did that. They shut us down and we couldn't do much with their bullpen.

Two years ago, the Giants' rotation recorded 11 quality starts in their 15 postseason games. Their current struggles, Posey said, are "a little surprising. But I don't think that it's anything that they can't turn around."

© Copyright The Sacramento Bee. All rights reserved.

• Read more articles by Matt Kawahara

Order Reprint