"I think that Gattis, you know he's going to get four at‑bats," Gonzalez said. "You don't know if he's going to get the ball hit to him in the first seven innings. So that's the theory that we go with him in the outfield."
Despite making just 91 starts (105 total games) during the regular season, the converted catcher led all Major League rookies in RBIs (65) and ranked second in home runs (21).
Meanwhile, Upton struggled heavily at the plate during the regular season, hitting just .184 with nine home runs and 26 RBIs in 126 games played.
Gattis had defensive troubles in the outfield during Game 1 of the series. In the second inning, he was unable to run down a catchable two-out RBI double by A.J. Ellis.
Upton replaced Gattis in left field during the final two innings of Friday's game.
"We could play the best offensive outfield early in the game, and then we have the capability of improving defensively with B.J. or Schafer, depending on which way we want to go," Gonzalez said.