This year the 19-year-old outfielder knows manager Davey Johnson is going to give him a chance.
"It's huge to have a manager on your side," Harper said Monday. "I'm really excited to come in here and play. I'm going to come in here, work as hard as I can, keep my mouth shut and play."
Johnson said he told Nationals general manager Mike Rizzo to "definitely keep an open mind on this young man." Although the Nationals have since signed some veterans to compete for a job, Johnson said Harper is "still in the mix to have an opportunity."
That's all Harper wants -- an opportunity. He'll need to improve on his play in the outfield, his baserunning and his patience at the plate.
"If I can help them out, I can make the decision harder," he said. "If I can't, then it's going to be easy for them."
The decision on Harper could have a big impact on a number of Nationals this season, especially Jayson Werth, who could be moved from right field to center to make way for the first pick of the 2010 amateur draft.
Harper played in 109 minor league games for the Nationals, before a hamstring injury ended his season with Double-A Harrisburg. He finished with a .297 batting average, 17 homers and 58 RBIs.
Given that he had just 387 at-bats at the minor league level, he will have to convince the Nationals he is ready for major league pitching. Getting sent back to the minors would be disappointing.
"Even last year, it was a disappointment," he said. "Hopefully, things work out that we don't have to talk about me going down to the minors."
In his one year as a professional, Harper has learned to try to understand the grind of playing every day. He plans to spend more time in the weight room during the season to keep up his strength.
If there is an area of his game he really wants to improve on, it's his defense.
"I think I can really get better out there -- throwing guys out, and things like that," he said. "I think I really got a little bit better in Harrisburg at throwing the ball and not trying to amp up and throwing it 10 rows back in the stands. I want to be a Gold Glove out there. I don't want to just be known as a hitter."
Johnson said there are realistically only three positions open on the Nationals roster: fifth starter, utility player and outfield.
First-round pick Anthony Rendon said he has been told he will play third, shortstop and second for the Nationals during his first professional spring training. He also understands "there's a really high chance I'm not going to make the team" and is prepared to start the year in the minor leagues.
Meanwhile, Rizzo said he had a phone conversation with Mike Cameron last week in which the veteran outfielder told him he was enjoying watching his son play high school baseball and that he wasn't mentally or physically ready to play. The 39-year-old is retiring after 17 seasons.
"He just didn't want to come in here and not give 100 percent and embarrass himself and embarrass the team," Rizzo said.