The first professional sign of struggle from Bryce Harper — the first indication that major league baseball cannot be conquered at age 19 — has drawn from him a new feature: defiance.

It doesn’t come from anger, but rather self-assurance. He ignores the numbers and says he is not in a slump. He mentioned that he felt “all over the place” at the plate last week, and later he was asked to further explain what he meant. “I feel good now,” he said. “I don’t really want to talk about that.”

And still, over the next week of games Harper played for the Washington Nationals, he could not improve his statistics. He has instead continued to come to grips with, and try to extricate himself from, his first prolonged struggle in the majors. Harper’s initial two months made him an all-star and led to favorable comparisons to the best seasons ever by a teenager. His third month has reduced his season, in sum, to league average and made him confront baseball’s defining challenge. He has had to face failure.

Harper’s unassailable confidence remains. When he exploded into the majors, he shrugged and insisted he could play better. As his batting average has dwindled, he has calmly suggested he is just fine, not the least bit frustrated. Every time questions are raised, he will not question himself.

“I don’t change anything,” Harper said. “I don’t try to change anything. My swing has worked since I was 7 or 8 years old. There’s nothing to be changed. It’s just things that happen. It’s the process of trying to stay within yourself and trying to do what you’ve been doing your whole life. You know, not chase their pitches, get that one pitch in your zone and hit it.”

The difficulty of getting that one pitch became an issue last week in Houston. Harper struck out looking on two controversial calls by home plate umpire Angel Hernandez. Manager Davey Johnson gave Harper the next day off to “let him take a step back.” Johnson sensed frustration. Harper said that was not the case.

“I’m not frustrated at all,” Harper said. “I haven’t been frustrated all year. The only thing I’m frustrated about is the other 24 guys I let down.”

He also felt wounded by calls against him. He said opposing pitchers had been getting strike calls “two or three inches off the plate,” and had been taking advantage. Harper responded by not changing. He will not expand his strike zone. He will not swing at pitches he perceives to be balls, even if umpires keep calling them strikes.

“I’m going to stick with my plan as best I can,” Harper said. “I think I should have 100 walks. I think if I’m looking at pitches and trying to find that mistake, I think when you’re down in counts and not getting that mistake it really hurts you. I just try to go up there and battle as best I can and try to get on base for the guys behind me.”

Facing adversity

When Harper debuted in late April, he became the youngest major leaguer in seven years. The Nationals did not consider his place in the majors permanent. His presence alone, as an everyday outfielder batting second for a first-place team, is remarkable.

Since the second half began, though, it has been an undeniably rough patch for Harper. Through Friday, he was batting .173 with a .273 on-base percentage and a .260 slugging percentage since the all-star break. There is a stat called OPS+ that calibrates a hitter’s on-base plus slugging percentage based on ballpark factors to a scale in which 100 is league average. Harper’s OPS+ on the season is 100.

On June 15, Harper’s .922 OPS (on-base plus slugging percentage) stood as the highest for a teenage hitter since at least 1900. It has dropped to .742, which is ninth-best among teenagers since 1900, better than hitters such as Al Kaline, Robin Yount and Alex Rodriguez. He is still in rarefied air, even after his slump.

But the slump remains. Despite his outward confidence, teammates and coaches have sensed him feeling the pressure.

“He gets frustrated, just like everybody else,” third baseman Ryan Zimmerman said last week. “For a while there, you could tell he was trying to do a little too much, swinging at a lot of first pitches. Swinging at the first pitch is fine, but it’s pretty much for if you can find a pitch you can do some damage with. I think one of the best things about him when he first came is, he could work a walk, see some pitches.

“He’s so good with two strikes that he shouldn’t be worried about it. When he gets two strikes, he buckles down. For a 19-year-old, he has a really good judgment of the strike zone. Nobody wants to struggle. Nobody wants to do bad. When you do, it’s just natural to try and do something to get back to where you were. He’ll learn. He’ll get back to where he was.”

‘Focus on the right things’

Before a game last weekend, hitting coach Rick Eckstein chatted with Harper in the batting cage. His message was not about mechanics. He told him, “Focus on the right things.”

“That’s what he has to do,” Eckstein said. “There’s a lot of distractions out there. You have to focus on the right things. He expects so much out of himself that sometimes, with guys that are as talented as he is, you have to try less, and not overthink the process and try to do too much. Let your talent speak. I’ve been very proud of everything he has done on the field and the way he’s gone about it.”

One National League scout — who requested anonymity because his team does permit him to speak publicly about opposing players — watches the Nationals frequently and agreed with Harper about the changes he should make: none. He said Harper’s struggles have sprung from typical challenges for rookies, including something such as facing left-handed relief specialists for the first time.

“The bottom line is, he’s 19 years old and he’s going to have to make adjustments as he goes forward,” the scout said. “It’s part of the game. He’s been a violent hitter. He gets to his front side really quick. Teams are probably just changing speeds on him and keeping him off-balance. It’s time for Harper to adjust. You know he will at some point.

“It’s unfair to expect him to do what he first did coming out [at his age]. Nobody in the history of the game has done that. It’s just a learning curve. I don’t think he needs any major adjustments in his swing.”

As he handles his slump, Harper has not changed, in either his swing or his routine. He arrives at the park early and sits in a cold tub. He smashes balls off a tee, then ones thrown by a coach from a short distance, and then on the field during batting practice. It is the same swing that made him a phenom early in the season, and the same swing, he believes, that will soon break his drought.

“It’s just a matter of time until you get going,” Harper said. “That’s baseball. It’s humbling. Sometimes you hit .180 and other times you hit .350. That’s just the game of baseball.”