The move comes on the heels of Rick Ankiel missing time with a tight left hamstring. In fact, Johnson said that if Harper had been healthy, he would have made the move a week ago had he known Ankiel would be out. Ankiel hurt the hamstring against the Marlins this past Friday.
Harper, who also missed time because of a tight left calf, played his first game since March 6 and went 0-for-2 with a walk. He said his calf did not cause him problems during the game.
Harper deals with attention deficit disorder and said it was tough watching the games on the bench while he was injured.
"My ADD kicked in there a little bit. It's kind of hard to sit on the bench and just watch," Harper said. "I was trying to take as much as I could out of everything. The calf felt good a couple of days ago. I just didn't want to push it, and I understood where [the team was] coming from. I made the right decision, I came back tonight and I felt good."
Before Wednesday's game, Johnson warned the assembled media not to draw conclusions when it comes to Harper's future in the outfield.
"I'm looking at other options. I would have done it a week ago before [Harper] got hurt," Johnson said. "Again, I'm looking for the best fit for this team. He is still a part of that. Again, you are trying to draw conclusions [and we have 21 games to go]. I certainly don't have my 25 people."
Harper said he was excited to learn that he was playing center field against the Braves. He has often pointed out that center field is his favorite position.
"It's a lot easier to play out there because of the angles to the ball and seeing the whole field," Harper said. "It's one of my favorite spots. It's good to get out there."
Harper made two putouts in the game. His toughest play came in the fifth inning. With runners on first and second and no outs, Dan Uggla hit a Tom Gorzelanny pitch to center field. Harper slipped, but he managed to catch the ball and threw to second base as Chipper Jones advanced to third.
"I felt good out there. I felt relaxed," Harper said.
When he was drafted first overall in the 2010 First-Year Player Draft, the plan was to put Harper in center field after spending most of his formative years as a catcher. But when he started playing professional baseball, Harper was a corner outfielder. He played right field for Class A Hagerstown and left field for Double A Harrisburg. There was a feeling that his routes were better playing the corner positions.
Entering Thursday's action against the Yankees, Harper is 5-for-13 (.455) in five exhibition games. He believes that he still has a chance to make the Nationals' Opening Day roster and indicated that he was misquoted Tuesday when he told a reporter that he probably wouldn't make the team because of his calf injury.
"Yesterday, I don't know what happened, but I know for sure I'm trying to make this club," Harper said. "I want to go up there and win. I've never had that mentality to say, 'Ah, probably not,' or 'I don't want to make the club.' I'm shooting to be one of the top 25 guys on this team, get up to D.C. and try to win. That's my main goal."
General Mike Rizzo said early Wednesday that the team has not made a decision on Harper's future.
"Of course, we haven't made a decision," Rizzo said. "There are 21 games left in Spring Training. The injury was a setback for him, as far as costing him days, at-bats and his learning curve. But we have a lot of time left in Spring Training. We are going to do what's best for him and his development. We'll see where it takes us toward the end of Spring Training."
Harper is expected to play against his favorite team as a kid -- the Yankees -- the next two days. He said he was looking forward to facing left-hander CC Sabathia on Friday in Tampa, Fla.
"Oh, man it's going to be fun," Harper said. "Even [Michael] Pineda tomorrow. You have a guy who pitched for Seattle and was great. He came over to the Yankees, of course. He is going to be fun to face tomorrow. It's going be kind of crazy to have CC -- a freakin' train -- coming at you."
Bill Ladson is a reporter for MLB.com and writes an MLBlog, All Nats All the time He also could be found on Twitter @WashingNats. This story was not subject to the approval of Major League Baseball or its clubs.