ST. LOUIS -- Manager Bruce Bochy implemented minor changes in the Giants' lineup Thursday that he hoped would have a major effect.

Flip-flopping Pablo Sandoval and Buster Posey in the batting order was among the changes made for Game 4 of the National League Championship Series against St. Louis. Posey hit third and Sandoval moved to cleanup, spots they each occupied just once during the regular season.

Entering Thursday with a .161 batting average (5-for-31) and no RBIs in the postseason, Hunter Pence dropped from fifth to sixth in the order. Hector Sanchez, who started at catcher to complete his usual pairing with Tim Lincecum, replaced Pence in the No. 5 slot. With Sanchez behind the plate, Posey started at first, as he did 29 times in the regular season. Brandon Belt was benched.

"It's a game of adjustments," Bochy said.

Bochy had a pregame chat with Pence to boost the right fielder's spirits. During San Francisco's 3-1 loss in Wednesday's Game 3, Pence grounded into an inning-ending double play with runners on the corners in the third inning, hit into an inning-ending forceout in the fifth and struck out with runners on first and second and one out in the seventh.

"He was pretty hard on himself after the game," Bochy said. "I just said, 'We don't do this here.' We all could have done something to help in that ballgame. I looked at it myself and thought of things I could have done different to help us win. But he took the full responsibility, which he shouldn't."

Benching Pence, moving Gregor Blanco from left field to right and installing Xavier Nady in left field was an option, but if Bochy considered it, he did so only briefly. Speaking with beat reporters who cover the Giants, Bochy didn't mention Pence's name but explained his philosophy regarding replacing top performers who are slumping.

"I believe that you need certain players in the lineup," Bochy said. "You need them for their presence and their energy that make their teammates respect them. I don't believe you sit a player like that unless he's lost. If you have an everyday player who gives it everything he has and you know what he means to the club, I think he should be out there."

Since Barry Zito is scheduled to pitch Friday's Game 5, Sanchez, who caught 25 of the left-hander's 32 starts, could start two straight games.

"We'll see how it goes tonight," Bochy said.

Bumgarner 'excited' to contribute in relief

ST. LOUIS -- Madison Bumgarner, the young left-hander excused from the Giants' rotation for the remainder of the National League Championship Series, becomes a third southpaw in San Francisco's bullpen.

Javier Lopez and Jeremy Affeldt will remain on the front burner when manager Bruce Bochy needs a lefty. Bumgarner does not figure to appear unless needed for long relief earlier than the sixth inning.

However, Bumgarner takes his seat in the bullpen with the same positive attitude as did Tim Lincecum earlier this postseason.

"He's excited about helping the club out, coming out of the bullpen," Bochy said prior to Thursday night's Game 4. "I think he understands why we're going that route and he's all in on this, helping us out in the bullpen. He is available, and part of it is the player accepting what you're asking. And he has, so he's all set to go."

Bumgarner's professional relief experience is minimal, but exceptional. His last appearance out of the bullpen came in Game 6 of the 2010 NLCS in Philadelphia, where he worked two shutout innings of the Giants' 3-2 pennant-clinching win.

His only three other Major League relief appearances came during his brief 2009 debut. On those occasions, he hurled a total of 4 2/3 shutout innings. Othewise, Bumgarner worked once in relief in 63 Minor League games.

Add it up, and he has started 156 of his 160 pro games.