Belt has just one hit in his last 24 at-bats and finished the latest six-game road trip with eight strikeouts in 20 at-bats.
"We're going to get his confidence back, and he said it has been shaken a little bit," Bochy said. "Well, you're forced to make a move when you hear that."
Sandoval said he was informed that he was shifting to first base when he arrived at the ballpark Monday. He has appeared in 57 career games at first base and started there six times in 2011, but has not started there yet this season. Sandoval took ground balls at first base before the game, which he said was the first time he has done so this season.
"I'm just going to do my best to play my game and win the game," Sandoval said. "No matter where I play, I'll be playing hard and just trying to catch the ball and make the play."
Sandoval said he has to borrow Buster Posey's glove when he plays first, and that he would be fine with more playing time there.
"If I play every day, I'm going to be happy no matter what," Sandoval said.
Schierholtz got the start after hitting 2-for-5 with two home runs against the Phillies on Sunday, while Blanco is batting .208 (5-for-24) since the All-Star break.
"[Schierholtz] hit two home runs; that's a pretty easy one," Bochy said. "But even before that, he was having some pretty good at-bats. It's similar to what we talked about with Brandon -- Blanco has been battling there a little bit, and here we are getting a shot in the arm with Nate."
Bochy said Belt especially needs to work in the batting cage to regain his confidence and work on making more contact while he sits out of the starting lineup.
"He needs a break to get that back and get back to getting good swings and making contact," Bochy said. "That's become an issue, eight strikeouts in the last 20 at-bats. He's not that kind of hitter, so it's obvious he needs a break right now."
Belt is hitting .231 in 216 at-bats this season, and Bochy declined to say whether the Giants have considered sending him down to the Minors.
"Brian and I talk about a lot of things, especially now with the Trade Deadline coming up," Bochy said. "I'll leave it at that."
Belt has worked on his swing and batting stance through his struggles all season, though Bochy said that regaining confidence will be the most important step for Belt.
"I think it's probably more mental than mechanical, but this is a tough game," Bochy said. "You need to man up and battle through these things. We all go through it, and we all have your tough days and times, but at the same time, the only thing you do is keep working and believe that you're going to get through it. You have to keep that confidence."