The most compelling subplot of Nationals spring training arrived early this morning, early enough to sit quietly at his locker for 15 minutes. He chatted with Ryan Zimmerman about a new pair of sneakers, stretched out his pants to his specifications and organized his locker. And then Bryce Harper walked out to a backfield to take batting practice.

Harper is determined to make the Nationals at 19, no matter the long odds against the Nationals choosing him for a spot in their opening day roster. Manager Davey Johnson told General Manager Mike Rizzo this winter “he should definitely have an open mind” about Harper. With spring beginning and the offseason moves finished, Harper is “still in the mix to have an opportunity,” Johnson said.

Harper faces a mountain of questions in his hope to make the opening day roster. With less than 600 professional plate appearances, has he developed enough? After he tore a hamstring last August, can his body handle a full major league season? Fully embracing his generation’s proclivity for personal exposure, can he display the professionalism Nationals management demands?

He’ll try.

“I’m going work as hard as I can, keep my mouth shut and play,” Harper said. “I’m going to make their decision hard as much as I can. I want to be up here. I want to play, and I want to play in D.C.”

Harper arrived at spring training last year saying he wanted to make the team despite obvious evidence that he would not. The Nationals ended up starting him at Class A Hagerstown, the lowest level possible. But as Johnson watched him during spring as a consultant, “I got the feeling it wouldn’t have been overpowering for him” to play in the majors.

“Even last year, I was disappointed,” Harper said. “I came here, and I wanted to make the team last year. This year, I’m trying to come here and make the team. Hopefully, things work out and we won’t have to talk about me going down to the minors.”

The Nationals have insisted only Harper’s preparedness will determine whether or not he starts 2012 in the majors. But there are also business reasons to justify him starting in the minors. If the Nationals delay his arrival until roughly mid-May, they would guarantee another full year or his service before he becomes eligible for free agency. The Nationals would have to sacrifice a full season of him at 25 for a month of him at 19.

The Nationals admit that Harper’s sheer ability will not be the only factor. Harper’s “maturity” is often raised as an issue, but “professionalism” may be the better word. Harper has kept an active Twitter account, frequently answering questions from fans in a way that may have rankled the front office.

“I like interacting with fans,” Harper said. “I like letting them know who I am and what I am. That’s just the way I am. I want everyone to know the real me.”

Harper has not shied from provocative quotations, including a comparison of himself and Joe Namath. It has nothing to do with how well he can hit a curveball. His behavior does matter when the Nationals evaluate his capacity to act like their definition of a big leaguer.

“I’m going to get blown up either way, whether I say something right or say something wrong,” Harper said. “That’s just how it’s going to be. There’s nothing I can really do about that. Maybe there’s sometimes I should keep my mouth shut. I need to grow up in that aspect, I guess. But I feel good about what I say, and I’m not going to back down from anything.”

On the field, Harper said he hopes to improve in the outfield, where he has only been playing full time for about 18 months; he was a catcher during his truncated college career.

“I can really get better out there,” Harper said. “Throwing guys out, things like that, I think I really got a little bit better [last year] at Harrisburg. Throwing the ball this winter, I’m not trying to amp up and throw it as hard as I can and throw it 10 rows back in the frickin’ stands. I made a lot of progress in the outfield. I want to be a Gold Glove out there, too. I don’t want to be just known as a hitter.”