Belt is struggling, batting .183 with no home runs and five RBIs. He has five hits in his last 24 at-bats.
Joaquin Arias started at first and batted sixth in the lineup. He entered the game 3-for-12 this season. Against Padres starter Eric Stults, Arias is 4-for-10 with one home run.
"This isn't a case where he's getting benched," Bochy said of Belt. "But we need to get Arias out there. [Belt] might miss a couple of games."
Bochy said he and Belt spoke privately before Sunday's game about "a couple of things, between Brandon and I."
Belt is a career .209 hitter in the month of April.
Willie Bans is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.