Since being called up to the big leagues in September he has seen very limited action -- six plate appearances, four of which came as a pinch-hitter -- and only seven innings in the outfield.
With A.J. Pollock, Ender Inciarte, David Peralta and Yasmany Tomas already fighting for time in the outfield, O'Brien's best opportunity of getting to the big leagues next year is behind the plate.
D-backs manager Chip Hale said O'Brien recently approached the team about moving back behind the plate.
"I think he does want to get back behind the plate," Hale said. "So that will be his decision. He's shown up here that he can hit, he's a Major League bat. Obviously being able to catch would help him come here and be here sooner."
• Shortstop Nick Ahmed had an MRI taken of his ailing back, and it appears his season is over. Ahmed injured his back making a diving stop while the team was in Los Angeles last week.
"Nothing serious, but there are some issues in there with bruising and different things," Hale said. "I do not think he's going to be able to play again this season. He'll be fine, but we just don't want to push it and re-injure him."
• D-backs closer Brad Ziegler was not with the team Tuesday night as his wife gave birth to a baby girl Monday night in Kansas. Hale said he was not sure when Ziegler would return to the team.
Steve Gilbert is a reporter for MLB.com. Read his blog, Inside the D-backs, and follow him on Twitter @SteveGilbertMLB. This story was not subject to the approval of Major League Baseball or its clubs.