Johnson believes Harper, 19, can be the Opening Day right fielder if the team decides to move Jayson Werth to center field.
"But I think that the main thing is ... could he handle it mentally? And I think in his mind, he's already figuring to be starting on the club, if you ask him," Johnson said recently about Harper. "And I haven't talked to him, but I know that he's done everything in his whole life to succeed at a higher level and compete with the best. But I think [Harper is] pretty mature. I don't look at him age-wise, as I probably should."
How did Harper feel after he heard that Johnson is going to give him every chance to make the 25-man roster?
"I feel really positive about going to Spring Training this year," Harper said via telephone. "I really feel I have a legit shot at making the club. We have a lot of guys coming in -- veteran guys that could really teach me how to approach the game. ... I'm really excited for this year.
"I've been working my butt off this offseason, getting ready to go out there and doing outfield stuff, working on running and jumping -- everything that consists of trying to make this team. To have Davey on my side, that a very big plus going in there."
It was a plus that Harper, who was the first overall pick in the 2010 First-Year Player Draft, had a productive season in his first year in pro ball. In 109 games, he hit a combined .297 with 17 home runs and 58 RBIs for Class A Hagerstown and Double-A Harrisburg.
The success in the Minor Leagues carried into the Arizona Fall League. In 93 at-bats for the Scottsdale Scorpions, Harper hit .333 with six homers and posted a .400 on-base percentage.
"It was a really good year. I had a lot of fun, especially going to the AFL again," Harper said. "That was a blast. I swung it pretty well. But the big thing is, there were so many good guys around, I think that was huge -- I had a great group of guys that really helped me out and made me one of the guys."
Harper credits his success last season to Washington outfield and baserunning coordinator Tony Tarasco. Yes, Tarasco taught Harper the fundamentals when it came to playing the outfield and running the bases. But Harper learned a lot more.
Tarasco often reminded Harper to stay focused on playing for Hagerstown or Harrisburg. Tarasco told him not to think about playing in the big leagues -- yet.
"Tony Tarasco was the biggest guy that really helped me out," Harper said. "He sat down with me and talked to me about the outfield and running the bases. He helped me out so much this [last] year. I wouldn't be where I'm at right now without him.
"The biggest thing he told me was, 'You are in Hagerstown. So your head needs to be out of D.C. .. Play hard where you are at and not worry about whatever things are going on around you. Be you and you'll move.' I think that was the best advice he gave me."
Since entering pro ball, Harper has been prone to slow starts. What can he do to make sure that he doesn't start Spring Training in a slump?
"It's the adjustments I have to make," Harper said. "There were so many adjustments I had to make when I moved [to different] levels. I struggled in high school, I struggled in college, I struggled in low A, struggled in the AFL a little bit. That's how I am, I guess. I have to get into the flow of things, get going. Once I get going, I go headfirst into everything -- I go as hard as I can."
Harper doesn't plan to make any adjustments off the field. Known to speak his mind on Twitter, Harper plans to be himself. Harper is a sports history buff, and he would like to live his life the way Jets quarterback Joe Namath did during his heyday in the 1960s and early '70s. Namath was known to be flamboyant off the field, but backed it up by having a Hall of Fame career.
"I'm going to be my own person. There are a lot of professional athletes back in the old days that did what they wanted to do. That's how I'm going to be," Harper said. "I'm going to prove myself on the field, so I can be that kind of guy off the field. I'm not a clown off the field. I just say things ... I speak my mind and I think that's good. If I speak my mind and people know the real me, then they are going to like me more. I'm not a liar. I say things I want to say. That's how it is, I guess.
"A football player I can name is Joe Namath. ... He had that city life and everything like that, but he was one of the best quarterbacks to play the game. I can't say I'm like Joe Namath. ... He went out, he played, but he had fun. He had a night life, he had his own place, I think it was called Bachelors III. He had his own thing that he wanted to do. ... He was in the style, he did all those commercials, things like that. He loved it. I think that's huge. That's one side of me that I like. I'm not your typical, 'Hey, I'm going to be Johnny Good.' You are a baseball player. ... I'm going to have fun off the field, too."
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.