"It didn't play into it," Washington said before Thursday's game. "My main concern with Vlad is I'm trying to keep his bat in the lineup."
Guerrero, Texas' usual designated hitter, has to play in the field in the NL park. He was available off the bench for Game 2.
Nelson Cruz was back in right field after getting the start in left in Game 1. David Murphy started in left field for the Rangers.
Both of Guerrero's errors came in the eighth inning of the Rangers' 11-7 loss, when he let a ball roll by him and misplayed a liner. San Francisco tacked on three runs before Texas scored three times in the top of the ninth.
"He might have missed a couple of balls, but those balls he missed, and if they scored runs off of it, certainly didn't determine the outcome of the ballgame," Washington said. "It might have added some runs but it didn't determine the outcome."
Washington had indicated before the World Series that Guerrero might start only one of the first two games in San Francisco.
It was only the second game in the outfield for Guerrero since the start of September. While he has played 1,608 games in the outfield over 15 major league seasons, he has appeared in the field 20 times over the past two seasons.
Guerrero played only two of his 100 games in the outfield during an injury-plagued 2009 season with the Los Angeles Angels. He appeared in 152 regular-season games this year, 18 of them in the outfield.
Washington said he talked to Guerrero about his decision for Game 2, and the slugger understood what was happening.
"If we come back here for Games 6 and 7, I'm going to play Guerrero a game here too," Washington said. "We're here because of Vlad. So I'm supposed to play two games in San Francisco and not let him touch the field? It won't happen."